FIELD OF THE INVENTION
[0001] The present invention relates to a lighting device comprising a housing comprising
a circular aperture, a solid state lighting arrangement comprising at least one solid
state lighting element mounted in said housing and arranged to emit light towards
said circular aperture and a circular cover plate comprising a plurality of lens elements
movably mounted in said circular aperture.
[0002] The present invention further relates to a luminaire comprising such a lighting device.
BACKGROUND OF THE INVENTION
[0003] Lighting devices based on solid state lighting (SSL) elements such as light-emitting
diodes (LEDs) are rapidly increasing in popularity because such devices are considered
an energy-friendly alternative to traditional lighting devices such as incandescent
or halogen light bulbs. However, one of the main drawbacks of SSL element-based lighting
devices is the higher cost of such devices compared to their traditional counterparts.
Although this is offset by the superior lifetime of the SSL element-based lighting
devices, this nevertheless forms a barrier for further market penetration of the SSL
element-based lighting devices.
[0004] Part of the reason for the higher cost of SSL element-based lighting devices is that
SSL elements generate light having completely different beam characteristics than
for instance incandescent lighting devices. For this reason, SSL element-based lighting
devices tend to comprise optical elements such as collimators and/or lenses to create
a lighting device producing a desirable illumination profile, e.g. a spot light or
the like.
[0005] It is not always apparent to the consumer which type of SSL-based lighting element
is best suited for the consumer's needs. This may lead to the consumer purchasing
one or more SSL-based lighting devices only to find that the devices do not produce
the desired luminous output. This of course is entirely unsatisfactory. Also, the
consumer may wish to use the SSL element-based lighting devices for different applications,
in which case some configurability of the luminous output of the SSL element-based
lighting devices is desirable.
[0006] EP 2,314,912 B1 discloses a LED lamp with an infinitely adjustable radiation angle whereby several
LEDs are located on a carrier plate and a lens plate including a lens array of Fresnel
lenses is located at an adjustable distance in front of the carrier plate. The lens
plate is located in a retaining ring which with its outer contour fits into the guide
thread of a guide ring that itself is turnable guided. The guide ring may be turned
such that the retaining ring with the lens plate is secured by means of the side guides
in the turning movement of the retaining ring to the LED plate depending on the turning
direction either toward or away from this, and whereby the defined stages of the radiation
angle between 10° and 60° are set by locking positions of the retaining ring or are
indicated by marks on the retaining ring.
[0007] A drawback of this LED lamp is that the optical performance of the Fresnel lenses
is typically dependent of the distance of the lens to the LED, i.e. has an optimal
distance to the LED. If the Fresnel lens is positioned at a suboptimal distance, the
luminous output of the lamp may be negatively affected. Also, if the Fresnel lens
array is too close to the LEDs, overheating may occur. Consequently, although the
LED lamp of
EP 2,314,912 B1 can produce beam angles in the range of 10° to 60°, the luminous output of the LED
lamp at some of these beam angles may be unsatisfactory.
SUMMARY OF THE INVENTION
[0008] The present invention seeks to provide a lighting device according to the opening
paragraph that may be reconfigured in a satisfactory manner.
[0009] The present invention further seeks to provide a luminaire comprising such a lighting
device.
[0010] According to an aspect, there is provided a lighting device comprising a housing
comprising a circular aperture; a solid state lighting arrangement comprising at least
one solid state lighting element mounted in said housing and arranged to emit light
towards said circular aperture; and a circular cover plate mounted in said circular
aperture, said circular cover plate facing said arrangement and comprising M different
optical elements, wherein M is a positive integer having a value of at least 2, wherein
the cover plate is fitted such that it can be rotated in the plane of said aperture
between M positions, wherein in each of said M positions a different one of said optical
elements is aligned with the at least one solid state lighting element.
[0011] The lighting device of the present invention includes a plurality of different optical
elements that are each selected to produce a desirable luminous output characteristic
for the lighting device. As the distance between the different optical elements and
the SSL elements of the lighting device is well-defined, i.e. does not vary due to
the fact that the cover plate is rotated in the plane of the aperture only, it can
be ensured that the optical elements produce the desired luminous flux, whilst overheating
may also be prevented. Consequently, a lighting device is provided that produces satisfactory
luminous outputs in each of its optical element configurations. It is furthermore
noted that although some embodiments of the lighting device may comprise redundant
optical elements in each of its configurations, i.e. optical elements that are not
in use, such optical elements can be provided in a cost-effective manner and therefore
do not significantly add to the cost of the lighting device.
[0012] In an embodiment, the solid state lighting arrangement comprises a plurality of solid
state lighting elements distributed over N locations, wherein N is a positive integer
having a value of at least 2; and the circular cover plate comprises M*N optical elements
organized in M groups of different optical elements, wherein in each of said M positions
the optical elements of one of said groups are aligned with the solid state lighting
elements in the N locations on said surface. The presence of a plurality of SSL elements
is preferred to ensure that the lighting device produces sufficient luminous output.
[0013] The plurality of solid state lighting elements may include solid state lighting elements
of different color and/or solid state lighting elements of different power. The solid
state lighting elements in a first of said N locations may be different to the solid
state lighting elements in a second of said N locations.
[0014] In an embodiment, the different optical elements comprise lenses having different
optical characteristics such as different optical power.
[0015] In an embodiment, the different optical elements comprise diffusers having different
diffusion characteristics.
[0016] In an embodiment, the different optical elements comprise different color adjustment
elements.
[0017] The circular cover plate may be mounted in said circular aperture such that it can
be toggled between a locked position and a released position in which the circular
cover plate can be rotated in the plane of the circular aperture. For instance, the
circular cover plate may be toggled between said locked position and said released
position by pushing the circular cover plate towards said surface. This allows for
a straightforward switching of the circular cover plate between the different optical
functions of the lighting device.
[0018] In an embodiment, the housing comprises a central recess and the cover plate comprises
a central protrusion spring-loaded into said central recess in order to facilitate
the toggling of the cover plate between the locked and released positions.
[0019] In order to assist a user in correctly aligning the cover plate in the circular aperture,
the circular aperture may comprise a plurality of guide slots around its inner perimeter
and the circular cover plate may comprise a plurality of guide members for engaging
with said guide slots such that the cover plate can only be put in its locked position
if the guide members correctly align with the guide slots. Alternatively, the circular
cover plate may comprise the plurality of guide slots and the circular aperture may
comprise the plurality of guide members around its inner perimeter for engaging with
said guide slots.
[0020] The lighting device may be a light bulb such as a spot light bulb. Suitable bulb
sizes include but are not limited to MR11, MR16, GU10, AR111, Par38, Par30, BR30,
BR40, R20, and R50 light bulbs. MR type light bulbs are particularly suitable.
[0021] According to another aspect, there is provided a luminaire comprising an embodiment
of the lighting device of the present invention. Such a luminaire may for instance
be a holder of the lighting device or an apparatus into which the lighting device
is integrated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Embodiments of the invention are described in more detail and by way of non-limiting
examples with reference to the accompanying drawings, wherein:
Fig. 1 schematically depicts a lighting device in accordance with an embodiment of
the present invention in a first configuration;
Fig. 2 schematically depicts a lighting device in accordance with an embodiment of
the present invention in a second configuration;
Fig. 3 schematically depicts a method of toggling a lighting device according to an
embodiment of the present invention between different configurations;
Fig. 4 schematically depicts a cross-section of a lighting device in accordance with
an embodiment of the present invention;
Fig. 5 schematically depicts a magnified aspect of the lighting device of Fig. 4;
Fig. 6 schematically depicts a cross-section of an aspect of a lighting device in
accordance with an embodiment of the present invention;
Fig. 7 schematically depicts a lighting device in accordance with another embodiment
of the present invention in a first configuration;
Fig. 8 shows a luminous distribution plot of the lighting device of Fig. 7;
Fig. 9 schematically depicts a lighting device in accordance with another embodiment
of the present invention in a second configuration;
Fig. 10 shows a luminous distribution plot of the lighting device of Fig. 9;
Fig. 11 schematically depicts an aspect of a lighting device in accordance with yet
another embodiment of the present invention;
Fig. 12 schematically depicts details of a part of the lighting device of Fig. 11;
and
Fig. 13 schematically depicts a part of the lighting device of Fig. 12 in an exploded
view.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0023] It should be understood that the Figures are merely schematic and are not drawn to
scale. It should also be understood that the same reference numerals are used throughout
the Figures to indicate the same or similar parts.
[0024] Fig. 1 schematically depicts a light exit surface of a lighting device 1 according
to an embodiment of the present invention. The lighting device 1 comprises a housing
10, which may be any suitably shaped housing. The housing typically comprises at least
one solid state lighting (SSL) element 12, which may for instance be mounted in the
housing in any suitable manner, e.g. on a suitable carrier such as a printed circuit
board and/or a heat sink. The at least one SSL element 12 may comprise one or more
light emitting diodes (LEDs), which may be inorganic or organic semiconducting LEDs.
In FIG. 1, the lighting device 1 is shown to have a single SSL element 12 by way of
non-limiting example only.
[0025] The housing 10 delimits a circular aperture 15, which may be dimensioned in accordance
with the size requirements of the lighting device 1. A cover plate 20 is rotatably
mounted in the circular aperture 15 such that the cover plate 20 can be rotated in
the plane of the circular aperture 15 as will be explained in more detail later. The
rotation may be in any suitable direction, e.g. clockwise as indicated by the dashed
arrow or counter-clockwise. In the context of the present application, rotation in
the plane of the circular aperture 15 means that the distance between the cover plate
20 and the at least one SSL element 12 does not change during the rotation. In other
words, the position of the cover plate 20 relative to the circular aperture 15 does
not change during the rotation.
[0026] In an embodiment, the cover plate 20 comprises a plurality of different optical elements,
i.e. elements having different optical characteristics. Generally, for a lighting
device 1 comprising N SSL elements 12, wherein N is an integer having a value of at
least 1, the cover plate 20 comprises M groups of different optical elements, wherein
M is an integer and is a multiple of N. Each of said M groups comprises N optical
elements that may be identical to each other. In other words, the lighting device
1 has M configurations, wherein in each of said M configurations one of the M groups
ofN optical elements is aligned with the N SSL elements, wherein the lighting device
1 may be switched between different configurations by replacing one of the M groups
of N optical elements with another of the M groups ofN optical elements, thereby changing
the optical manipulation of the luminous output of the lighting device 1, e.g. from
a narrow beam angle to a wide beam angle or vice versa.
[0027] In Fig. 1, M = 3 and N = 1 by way of non-limiting example. In other words, the cover
plate 20 of the lighting device 1 comprises a first lens 22, a second lens 24 and
a third lens 26 distributed in a radial pattern along the perimeter of the cover plate
20. The radius of the pattern typically matches the distance of the SSL element 12
to the central axis of the lighting device 1 such that each of the first lens 22,
second lens 24 and third lens 26 can be aligned with, i.e. positioned over, the SSL
element 12 in the different configurations of the lighting device 1. The first lens
22, the second lens 24 and the third lens 26 typically have different optical characteristics,
e.g. different optical powers such that the luminous output distribution produced
by the lighting device 1 can be altered when changing the configuration of the cover
plate 20. For instance, whereas in Fig. 1 the first lens 22 is aligned with the SSL
element 12, the cover plate 20 may be rotated clockwise as indicated by the dashed
arrow to align the third lens 26 with the SSL element 12, as is shown in Fig. 2. A
further rotation may align the second lens 24 with the SSL element 12 (not shown).
[0028] The different lenses of the cover plate 20 may be the same type of lenses, e.g. Fresnel
lenses, having different designs to achieve the different optical characteristics
or may be different lens types, e.g. a Fresnel lens, a dome lens and so on. The optical
elements may form part of the cover plate 20 in any suitable manner. For instance,
the cover plate 20 may comprise a plurality of apertures into which the optical elements
are fitted. Alternatively, areas of the cover plate 20 may be modified, e.g. etched,
to form the optical elements. In yet another embodiment, the cover plate 20 may carry
the optical elements, e.g. the optical elements are mounted on the cover plate 20.
Other feasible implementations will be apparent to the skilled person.
[0029] Fig. 3 schematically depicts a non-limiting example of a suitable mechanism for switching
the lighting device 1 between different configurations. In this embodiment, the cover
plate 20 is spring-loaded into the circular recess 15 of the housing 10 and can be
toggled between a working position in which the cover plate 20 is locked into place
in the circular recess 15 and an adjustment position in which the cover plate 20 is
released from the circular recess 15. In other words, the cover plate 20 is mounted
in the circular recess 15 by means of a self-locking push button mechanism.
[0030] The working position of the cover plate 20 is shown in (a). In order to release the
cover plate 20 from its working position in the circular recess 15, the cover plate
20 may comprise a central cap 25 acting as the push button. The central cap may be
pressed down to press the cover plate 20 into the circular recess 15 as shown by the
arrow in step (b). The pressure on the central cap 25 is subsequently released, which
leads to the cover plate 20 popping out of the circular recess 15 as indicated by
the upward arrow in step (c). This brings the cover plate 20 in the released position
in which the cover plate 20 can be (freely) rotated in the plane of the circular recess
15.
[0031] The cover plate 20 is subsequently rotated in the plane of the circular recess 15
as shown in step (d), in which for instance the alignment of the first lenses 22 with
the SSL elements of the lighting device 1 may be reconfigured to yield a configuration
in which the second lenses 24 are aligned with the SSL elements of the lighting device
1. The cover plate may comprise one or more alignment aids, e.g. markers 28, that
indicate the level of rotation required for the cover plate 20 to ensure that the
desired optical elements are appropriately aligned with the SSL elements of the lighting
device 1. Such markers 28 may have any suitable shape or form, e.g. may take the shape
of an arrow or triangle pointing at a guide member or guide slot of the cover plate
20. The circular recess 15 may for instance comprise a guide slot 115 for receiving
the guide member of the cover plate 20 or may instead comprise a guide member 115
for engaging with a guide slot on the cover plate 20. Generally speaking, the circular
recess 15 mat comprise a first guide element and the cover plate 20 may comprise a
second guide element, wherein the first guide element and the second guide element
are designed to engage with each other to ensure that the selected set of optical
elements is appropriately aligned with the underlying SSL elements.
[0032] Upon appropriately positioning the desired optical elements over the SSL elements
of the lighting device, the central cap 25 may be pressed down again into the circular
recess 15 to toggle the cover plate 20 from its released position into its secured
or operating position. This is shown by the downward arrow in step (e). The aforementioned
guide elements if present may be forced into their engaging position in this step,
e.g. by inserting a guide member into a matching guide slot and improper alignment
of the guide elements may prevent the cover plate 20 from being inserted into the
circular recess 15, thereby prevent incorrect alignment of the selected optical elements
with the SSL elements of the lighting device 1. By releasing the pressure on the central
cap 25, the cover plate 20 will ease into its operating position as shown by the upward
arrow in step (f).
[0033] Fig. 4 schematically shows a cross-section of the lighting device 1 as shown in Fig.
3, and Fig. 5 shows a magnified aspect of this cross-section. The housing 10 comprises
a self-locking pushing mechanism, comprising the end cap 25 engaging with a self-locking
push button mechanism 125. Such self-locking push button mechanisms are known per
se and will therefore not be explained in further detail for the sake of brevity only.
The lighting device 1 may further comprise a carrier 112 such as a PCB or the like
onto which one or more SSL elements 12 are mounted in any suitable manner. As can
be seen in FIG. 4 and 5, the first optical elements 22 in the cover plate 20, e.g.
first lenses, are positioned over the SSL elements 12 inside the circular recess 15.
[0034] Fig. 5 further shows an embodiment of the aforementioned first and second guide elements.
In this embodiment, the inner wall of the housing 10 delimiting the circular recess
15 comprises a trench acting as a guide slot 115 for receiving a protrusion on the
outer perimeter of the cover plate 20 acting as a guide member 120. The guide member
120 fits into the guide slot 115 and ensures that the first optical elements 22 are
appropriately aligned with the underlying SSL elements 12. Although not specifically
shown, it should be understood that the inner wall of the housing 10 may comprise
a plurality of such guide slots 115 and/or the cover plate may comprise a plurality
of such guide members 120 to ensure that for each optical element configuration an
appropriate alignment with the SSL elements 12 is achieved. It is of course equally
feasible if the inner wall of the housing 10 comprises the guide members and the outer
perimeter of the cover plate 20 comprises the guide slots, and it should be understood
that other suitably shaped guide elements may also be used.
[0035] Fig. 6 and 7 schematically depict an alternative embodiment of the lighting device
1 in which the SSL elements 12 are each mounted on a lens 14 such as a Fresnel lens.
The lenses 14 may be individual lenses or may form part of a lens plate 11 as shown
in Fig. 6. The use of a lens plate 11 facilitates the manufacture of the lighting
device 1 as only a single element has to be fitted into the housing 10 of the lighting
device 1. The cover plate 20 in this embodiment comprises groups of different diffusers.
In Fig. 7, two groups of diffusers are shown by way of non-limiting example; a first
group comprising first diffusers 32 and a second group comprising second diffusers
34. It will be understood that any suitable number of groups of different optical
elements, i.e. different diffusers, may be present in the cover plate 20 as previously
explained.
[0036] The cover plate 20 may be manufactured in any suitable manner. For instance, a transparent
cover plate 20 may be provided, e.g. made of a suitable transparent polymer such as
poly(methyl methacrylate) (PMMA), polycarbonate (PC) or polyethylene terephthalate
(PET), wherein selected regions of the cover plate 20 are etched or sandblasted to
form the desired diffusers. Alternatively, the cover plate 20 may be manufactured
using double injection molding techniques. Other manufacturing techniques will be
apparent to the skilled person. In an embodiment, the first optical element 32 may
be a transparent portion of the cover plate 20 such that the luminous output of a
SSL element 12 aligned with this optical element is only manipulated by the lens 14
over the SSL element 12.
[0037] Different diffusers may for instance be used to achieve different beam angle characteristics
of the lighting device 1. For example, in Fig. 7 a configuration of the lighting device
1 is shown in which the SSL elements 12 are aligned with the first diffusers 32 in
the cover plate 20. This produces a narrow beam angle of approximately 15° as shown
in the light distribution plot in Fig. 8. By reconfiguring the lighting device 1 such
that the second diffusers 34 are aligned with the SSL elements 12, for instance using
the reconfiguration mechanism as disclosed in detail in Fig. 3 and its detailed description,
a different beam angle may be generated. Fig. 9 schematically depicts the configuration
of the lighting device 1 in which the second diffusers 34 are aligned with the SSL
elements 12 and Fig. 10 shows the light distribution plot that is generated using
the configuration in Fig. 9. As can be seen in Fig. 10, a wider beam angle of approximately
30° is generated in the second configuration of the lighting device 1.
[0038] Fig. 11 shows yet another embodiment of a lighting device 1. Whereas in the lighting
devices of e.g. Fig. 1 and Fig. 7 the different optical elements were defined as circular
apertures in the cover plate 20, in the embodiment of Fig. 11 the first optical elements
22 are defined as such apertures and the second optical elements 24 are located in
between these apertures. This has the advantage that a higher density of optical elements
can be obtained on the cover plate 20, such that a higher density of SSL elements
12 may be used, thus producing a lighting device 1 that is capable of producing a
particularly high luminous flux. The cover plate 20 may be mounted in the circular
aperture 15 delimited by the housing 10 as previously explained with the aid of Fig.
1-5.
[0039] Fig. 12 depicts a cross-section of an aspect of the lighting device 1 along the lines
A-A shown in Fig. 11. In this embodiment, the first optical element 22 is a total
internal reflection collimator and the second optical element 24 is a donut-shaped
lens. Such optical elements for instance may be used to reconfigure the lighting device
1, e.g. change its beam angle, from a PAR-type lighting device in which the total
internal reflection collimators, e.g. Fresnel lenses, are in use , to a BR-type lighting
device in which the donut-shaped lenses are in use. It is noted that a TIR collimator
and donut-shaped lens are shown as different optical elements by way of non-limiting
example only. The skilled person may choose any suitable type of optical element,
e.g. lens or collimator, in order to match one of the configuration modes of the lighting
device 1 to a particular application domain.
[0040] Fig. 13 schematically depicts an embodiment of the cover plate 20 of the lighting
device 1 of Fig. 11 in an exploded view. The cover plate 20 is assembled from a lens
holder 220 onto which an annulus 222, e.g. an integrated lens package, comprising
the first optical elements 22 and the second optical elements 24, e.g. TIR collimators
and donut lenses respectively, is placed. A top plate comprising a first outer ring
224 and a second inner ring 224' engages with the lens holder 220 to form a housing
in which the annulus 222 can rotate. This housing prevents longitudinal movement of
the annulus 222 (movement in the direction perpendicular to the plane of the rings).
Instead of two separate rings, the top plate may also comprise a single ring engaging
with the lens holder 220 to prevent such longitudinal displacement of the annulus
222. The various components of the cover plate 20 may be made of any suitable material,
e.g. transparent polymers such as PMMA, PC or PET.
[0041] At this point, it is noted that the optical elements in the cover plate 20 are not
limited to beam shaping elements. It is for instance equally feasible that the different
optical elements are different color filters such that the lighting device 1 can produce
different colors in its different configurations of the cover plate 20. Alternatively,
the different optical elements may be different wavelength converting materials to
alter the color produced by the SSL elements 12. A non-limiting example of such different
wavelength converting materials is different phosphors.
[0042] In at least some embodiments, the cover plate 20 may comprise a combination of beam
shaping elements, e.g. lenses and/or collimators and color-manipulating elements such
as color filters such that in certain configurations the SSL elements 12 are aligned
with a group of beam shaping elements whereas in certain other configurations the
SSL elements 12 are aligned with color-manipulating elements.
[0043] In at least some embodiments, the SSL elements 12 of the lighting device 1 may be
identical. In some other embodiments, the SSL elements 12 may be different, e.g. SSL
elements producing different colors.
[0044] In some embodiments, the cover plate 20 may comprise M groups ofN optical elements
for a lighting device comprising N SSL elements 12 as previously explained. In other
words, in these embodiments the lighting device comprises more optical elements than
SSL elements such that in each configuration of the lighting device some of the optical
elements are not in use (i.e. are redundant).
[0045] However, in some other embodiments the number of optical elements may match the number
of SSL elements. This is for instance particularly interesting when the lighting device
1 comprises different SSL elements 12, e.g. SSL elements 12 producing different colors,
such that the lighting device 1 may have M different groups of N optical elements
and M different groups of N SSL elements 12. For instance, by aligning different optical
elements with different color SSL elements, the color output of the lighting device
1 may be tuned.
[0046] For example, a lighting device 1 may comprise a first group of yellow light SSL elements
12 and a second group of blue light SSL elements 12, and two groups of optical elements
for producing a narrow and wide beam angle respectively. In a first configuration,
the yellow SSL elements 12 may be aligned with the narrow beam angle generating optical
elements and the blue SSL elements 12 may be aligned with the wide beam angle generating
optical elements, whereas in a second configuration, the blue SSL elements 12 may
be aligned with the narrow beam angle generating optical elements and the yellow SSL
elements 12 may be aligned with the wide beam angle generating optical elements in
order to change the color characteristics of the lighting device 1.
[0047] In at least some of the aforementioned embodiments, the SSL elements 12 of the lighting
device may have different powers, i.e. produce different luminous intensities such
that the lighting device 1 may have M different groups ofN optical elements and M
groups of N SSL elements 12 of different power. For instance, by aligning different
optical elements with different power SSL elements, the luminous distribution of the
lighting device 1 may be tuned.
[0048] For example, a lighting device 1 may comprise a first group of lower power SSL elements
12 and a second group of higher power SSL elements 12, and two groups of optical elements
for producing a narrow and wide beam angle respectively. In a first configuration,
the lower power SSL elements 12 may be aligned with the narrow beam angle generating
optical elements and the higher power SSL elements 12 may be aligned with the wide
beam angle generating optical elements to produce a light distribution with higher
intensity at wider beam angles. In a second configuration, the higher power SSL elements
12 may be aligned with the narrow beam angle generating optical elements and the lower
power SSL elements 12 may be aligned with the wide beam angle generating optical elements
in order to produce a light distribution in which the higher light intensity is focused
in the center of the luminous output of the lighting device 1.
[0049] In some embodiments, the lighting device 1 is a light bulb such as a spot light bulb.
The light bulb may have any suitable size, e.g. MR11, MR16, GU10, AR111, Par38, Par30,
BR30, BR40, R20, and R50 light bulbs and any other suitable size.
[0050] The lighting device 1 according to embodiments of the present invention may be advantageously
included in a luminaire such as a holder of the lighting device, e.g. a ceiling light
fitting, or an apparatus into which the lighting device is integrated, e.g. a cooker
hood or the like to produce a configurable luminaire.
[0051] It should be noted that the above-mentioned embodiments illustrate rather than limit
the invention, and that those skilled in the art will be able to design many alternative
embodiments without departing from the scope of the appended claims. In the claims,
any reference signs placed between parentheses shall not be construed as limiting
the claim. The word "comprising" does not exclude the presence of elements or steps
other than those listed in a claim. The word "a" or "an" preceding an element does
not exclude the presence of a plurality of such elements. The invention can be implemented
by means of hardware comprising several distinct elements. In the device claim enumerating
several means, several of these means can be embodied by one and the same item of
hardware. 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.
1. A lighting device (1) comprising:
- a housing (10) comprising a circular aperture (15);
- a solid state lighting arrangement comprising at least one solid state lighting
element (12) mounted in said housing and arranged to emit light towards said circular
aperture; and
- a circular cover plate (20) mounted in said circular aperture, said circular cover
plate facing said arrangement and comprising M different optical elements (22, 24,
26, 32, 34), wherein M is a positive integer having a value of at least 2, wherein
the cover plate is fitted such that it can be rotated in the plane of said aperture
between M positions, wherein in each of said M positions a different one of said optical
elements is aligned with the at least one solid state lighting element.
2. The lighting device (1) of claim 1, wherein:
- the solid state lighting arrangement comprises a plurality of solid state lighting
elements (12) distributed over N locations, wherein N is a positive integer having
a value of at least 2; and
- the circular cover plate (20) comprises M*N optical elements (22, 24, 26, 32, 34)
organized in M groups of different optical elements, wherein in each of said M positions
the optical elements of one of said groups are aligned with the solid state lighting
elements in the N locations on said surface.
3. The lighting device (1) of claim 2, wherein the plurality of solid state lighting
elements (12) include solid state lighting elements of different color.
4. The lighting device (1) of claim 2 or 3, wherein the plurality of solid state lighting
elements (12) include solid state lighting elements of different power.
5. The lighting device (1) of any of claims 2-4, wherein the solid state lighting elements
(12) in a first of said N locations are different to the solid state lighting elements
in a second of said N locations.
6. The lighting device (1) of any of claims 1-5, wherein the different optical elements
(22, 24, 26) comprise lenses having different optical characteristics.
7. The lighting device (1) of any of claims 1-6, wherein the different optical elements
(32, 34) comprise diffusers having different diffusion characteristics.
8. The lighting device (1) of any of claims 1-7, wherein the different optical elements
comprise different color adjustment elements.
9. The lighting device (1) of any of claims 1-8, wherein the circular cover plate (20)
is mounted in said circular aperture (15) such that it can be toggled between a locked
position and a released position.
10. The lighting device (1) of claim 9, wherein the circular cover plate can be toggled
between said locked position and said released position by pushing the circular cover
plate towards said surface.
11. The lighting device (1) of any of claims 1-10, wherein the housing (10) comprises
a central recess and the cover plate (20) comprises a central protrusion spring-loaded
into said central recess.
12. The lighting device (1) of any of claims 9-11, wherein the circular aperture (15)
comprises a plurality of guide slots (115) around its inner perimeter and the circular
cover plate comprises a plurality of guide members (120) for engaging with said guide
slots.
13. The lighting device (1) of any of claims 9-11, wherein the circular cover plate comprises
a plurality of guide slots and the circular aperture (15) comprises a plurality of
guide members around its inner perimeter for engaging with said guide slots.
14. The lighting device (1) of any of claims 1-13, wherein the lighting device is a light
bulb.
15. A luminaire comprising the lighting device (1) of any of claims 1-14.