WO2013072881A1

WO2013072881A1 - Gobo arrangement

Info

Publication number: WO2013072881A1
Application number: PCT/IB2012/056485
Authority: WO
Inventors: Stefan Marcus Verbrugh; Reinhard Ruben Voorspoels; Ralph Kurt
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2011-11-17
Filing date: 2012-11-16
Publication date: 2013-05-23

Abstract

A gobo arrangement (200, 300, 400) comprises a first gobo holder (210, 310, 410) arranged to rotate around a first rotational axis (211, 311, 411), a second gobo holder (220, 320, 420) arranged to rotate around a second rotational axis (221, 321, 421) spaced apart from the first rotational axis, and a light receiving region (240, 340, 440) spanning between the first and second rotational axes. The gobo arrangement further comprises a set of at least two gobos (230, 330, 430) mounted to the gobo holders such that each one of the gobos is allowed to be exposed in the light receiving region. The present invention is advantageous in that the gobo arrangement has a reduced size.

Description

Gobo arrangement

FIELD OF THE INVENTION

The present invention generally relates to gobo arrangements for use together with spotlights for providing light projections. In particular, the present invention relates to gobo arrangements comprising two or more gobos for providing different light projections using the same spotlight.

BACKGROUND OF THE INVENTION

In entertainment lighting, gobo arrangements are used together with spotlights to create light projections e.g. on a stage. Such gobo arrangements typically comprise at least one gobo having transparent and non-transparent portions together forming an image or pattern. When the gobo is put in front of and is illuminated by the spotlight, a light projection corresponding to the gobo is provided. In other words, the gobo shapes the beam from the spotlight and thereby provides a light projection image. Normally, gobo arrangements comprise a lens system for projecting the beam shaped by the gobo on a remote surface (such as a stage).

For altering between different light projection images, the gobo in front of the spotlight may be manually changed or a so called gobo wheel may be used. A gobo wheel is a circular plate having several circumferentially arranged gobos. The gobo in front of the spotlight may be changed by rotating the wheel. The size of such a gobo wheel increases by the number of gobos included in the wheel, as well as by the gobo sizes. As the gobo size has to essentially correspond to the light output area of the spotlight, gobo wheels are normally used for lamps with small light output areas, such as high-intensity discharge (HID) lamps, whereby the gobo wheel can be made rather small. HID lamps provide sufficiently high light output (about 50 000 lumens) through a small light output area (with a diameter of about 20 mm). However, sometimes it is desirable to use other lamp types having larger light output areas, such as halogen lamps, because of their light characteristics. Typically, halogen lamps have to have light output areas of about 80 mm to provide sufficiently high light output (about 20 000 lumens). As a gobo wheel would be rather large and heavy if it was adapted to such spotlights (since the gobos would have to be larger), and in particular, if many gobos would be desired on the same wheel, the manual change alternative is normally used for such spotlights.

The advantages of light emitting diode (LED) based lamps have begun to be discovered within the field of entertainment lighting. LED based lamps have long life time, provide energy efficiency, and can electrically change light color without moving parts. However, the light output area of LED based spotlights preferably have a diameter of about 80 mm to provide a sufficiently high light output of about 10 000 lumens. Thus, using a conventional gobo wheel as a gobo arrangement for LED based lamps is not an appropriate alternative as it would imply a rather large and heavy gobo wheel. Further, manually changing gobos is a rather cumbersome and slow alternative.

An alternative gobo arrangement is disclosed in US2005/0207163, in which a digital mirror device (DMD) is used to shape light from a light source. However, a problem with such a gobo arrangement is that it is rather technically complex and expensive. In addition, DMDs have a rather small light output area with a diameter far less than 80mm.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome at least some of the above described problems, and to provide a gobo arrangement allowing altering between at least two gobos. It is also an object of the present invention to provide a gobo arrangement with a reduced size.

According to the invention, this and other objects are achieved by a gobo arrangement having the features defined in the independent claim. Embodiments of the invention are defined in the dependent claims.

Hence, according to the invention, a gobo arrangement is provided. The gobo arrangement comprises a first gobo holder arranged to rotate around a first rotational axis, a second gobo holder arranged to rotate around a second rotational axis spaced apart from the first rotational axis, and a light receiving region spanning between the first and second rotational axes. The light receiving region is adapted to be at least partly illuminated by a light source. The gobo arrangement further comprises a set of at least two gobos, each gobo mounted to the first and/or the second gobo holder such that each one of the gobos is allowed to be exposed in the light receiving region.

The present invention is based on the idea of arranging the gobos in a more space saving manner. With the present invention, alternation of the gobo exposed in the light receiving region is effected upon rotation of the first and second gobo holders around their corresponding rotational axis. The present invention is advantageous in that the gobo arrangement has a reduced size. In particular, a reduced size in a plane perpendicular to the beam direction (optical axis) of the light source is obtained, which is advantageous in that the gobo arrangement requires a smaller space when arranged between other lighting

equipments. With the present invention, many gobos, as well as relatively large gobos, may be provided without necessarily implicating an impractically large and heavy gobo arrangement. Thus, the present invention is advantageous when using light sources with a relatively large light output area, such as LED based lamps. Moreover, the present invention allows a faster and more automatized change of gobos compared to conventional manual change of gobos.

Further, the present invention is advantageous in that the gobo arrangement is largely mechanical, whereby it is technically less complex, as well as less expensive, compared to digitally generated light shapers.

In an embodiment of the present invention, a gobo of the set of gobos may comprise portions having different luminous transmittance, thereby defining an image (or pattern) to be projected on a remote surface (such as a screen or stage). For example, the gobos may comprise portions with different transparency and/or portions of different colors. The image may e.g. be a regular or irregular pattern, or a picture.

According to an embodiment of the present invention, the size of the light receiving region may match (or essentially correspond to) the size of one gobo of the set of gobos, whereby the size of the light receiving region and the distance between the rotational axes (and thus the whole gobo arrangement) may not be unnecessarily large. For example, the light receiving region (and the distance between the rotational axes) may be the same or slightly larger than the size of one gobo.

In an embodiment of the present invention, the first and second rotational axes are preferably (at least almost) parallel. It will however be appreciated that the two rotational axes do not necessarily need to be exactly in parallel and that the shape of the gobo may be adapted to the arrangement of the two axes.

According to an embodiment of the present invention, the gobos may be made of plastic, which is advantageous in that the weight of the gobos (and thus the whole gobo arrangement) is reduced. Conventional gobos adapted to halogen or HID lamps are normally made of a heat resistant material, such as metal or ceramics, since such lamps emit a lot of heat in the light beam. The present embodiment is preferable when using an LED based light source, which produces far less heat in the light beam, whereby a less heat resistant material, such as plastics, may be used for the gobos. The plastic gobos may e.g. comprise a transparent plastic film, on which an image or pattern is printed, a non-transparent plastic film, in which the image or pattern is cut out, or a rigid non-transparent plastic plate in which the image or pattern is cut out.

According to an embodiment of the present invention, the set of gobos may comprise more than two gobos, whereby several different light image projections may be obtained when using the gobo arrangement in a lighting system. The present embodiment is advantageous in that a plurality of gobos may be included while still providing a reduced size of the gobo arrangement, since the size of the gobo arrangement is less dependent on the number of gobos included in it compared to a conventional gobo wheel.

According to an embodiment of the present invention, the gobos may be arranged side by side at a flexible film, which at one of its ends is attached to and rolled up on the first gobo holder and at the opposite end is attached to and rolled up on the second gobo holder. The present embodiment is based on the idea of changing gobo by rotating the gobo holders and thereby scrolling the film in the beam of the light source until the desired gobo is exposed in the beam (in the light receiving region). In other words, different portions of the film, and thus, different gobos, are exposed in the light receiving region upon rotation of the gobo holders. The present embodiment is advantageous in that the size of the gobo arrangement is reduced, as the gobos not exposed in the light receiving region are rolled up on the gobo holders. In particular, the size of the gobo arrangement is reduced in the direction parallel to the optical axis (or beam), thereby facilitating placement of color filters or the like close to the gobo in the light receiving region.

In an embodiment, the film may be arranged to be rolled up on one of the first and second gobo holders simultaneously as it is unrolled on the other one of the first and second gobo holders upon alternation of the gobo exposed in the light receiving region, whereby the film may be kept in a strained (or non-slacked) position between the gobo holders.

In an embodiment, the first gobo holder may be formed by a first elongated, preferably cylindrical, member and the second gobo holder may be formed by a second elongated, preferably cylindrical, member, whereby the gobo holders have shapes suitable for rolling up the film.

According to other embodiments of the invention, the gobos may be arranged to pivot, preferably around the first and second rotational axes, into and out of the light receiving region. These embodiments will be described in more detail in the following. According to an embodiment of the present invention, each one of the gobos may be attached to one of the gobo holders such that each gobo is pivotally movable around the rotational axis of the gobo holder it is attached to. The present embodiment is based on the idea of providing a door-like arrangement for pivoting the gobos into and out of the light receiving region. When a particular gobo is used for light projection, it is positioned (and exposed) in the light receiving region and thereby in the beam from the light source. When that particular gobo is not to be used anymore (e.g. if another, or no, gobo is to be used), it may be pivoted out of the light receiving region, preferably by a rotational angle of at least 90° for avoiding blocking the beam. Preferably, an edge or at least a peripheral portion of each gobos may be attached to the gobo holders.

The present embodiment is advantageous in that rigid plastic, ceramic or metal gobos may be used, which have an improved robustness and durability. Further, the gobo arrangement according to the present embodiment may be adapted to lighting systems with halogen or HID lamps, which requires heat resistant gobos made of metal or ceramics.

In an embodiment, at least two gobos may be attached to one of the first and second gobo holders such that they are pivotally movable around the rotational axis of the gobo holder they are attached to, and preferably controllable, independently of each other. Hence, each gobo may be separately pivoted around the rotational axis, which means that one of the gobos may pivot into and out of the light receiving region while the other gobos may remain still.

Alternatively, the gobos attached to the one and the same gobo holder may be mounted fixed to each other, such that they simultaneously pivot upon rotation of the gobo holders. In that case, e.g. two gobos may be mounted to the one and the same gobo holder with an angle of 180° to each other (i.e. such that they point in opposite directions), whereby the gobos not being used for light projection do not block the beam of the light source.

In an embodiment of the invention, the first and second gobo holders may be independently movable, and preferably also independently controllable. Hence, one of the gobo holders may be rotated while the other one remains still.

According to another embodiment of the present invention, each one of the gobos may be divided into two pieces, wherein one of the two pieces is attached to the first gobo holder and the other piece is attached to the second gobo holder, wherein each one of the pieces is allowed to pivot around the rotational axis of the gobo holder it is attached to such that the two pieces are allowed to mate (or meet) in the light receiving region. The present embodiment is based on the idea of providing a double door-like arrangement for pivoting the gobos into and out of the light receiving region. Hence, when a particular gobo is used for light projection, its two pieces mate and are exposed in the light receiving region and thus in the beam from the light source. When that particular gobo is not to be used anymore (e.g. if another, or no, gobo is to be used), the two pieces may be pivoted out of the light receiving region, each one preferably by a rotational angle of at least 90° for avoiding blocking the beam.

In similarity with the previously described door-like embodiment, rigid plastic, ceramic or metal gobos may be used, which have an improved robustness and durability. The two pieces of each gobo may e.g. be manufactured separately, or in a single piece, which subsequently is split into two pieces. The present embodiment is advantageous in that the gobo arrangement has a reduced size, not only in the plane perpendicular to the direction of the light beam, but also in the direction parallel to the direction of the light beam, as merely a half (or a piece of a) gobo may point in that direction upon pivoting the gobos.

In an embodiment, the pieces of the gobos being attached to the one and the same gobo holder may be pivotally movable around the rotational axis of the gobo holder they are attached to, and preferably controllable, independently of each other. Hence, each gobo piece may be separately pivoted around the rotational axis, which means that the two pieces of one of the gobos may pivot into and out of the light receiving region while the pieces of the other gobos may remain still.

Alternatively, the pieces of the gobos attached to the one and the same gobo holder may be mounted fixed to each other, such that they simultaneously pivot upon rotation of the gobo holders. In that case, e.g. a maximum of four gobo pieces may be mounted to the one and the same gobo holder perpendicular to each other, such that the gobo pieces currently not being used for light projection avoid blocking the beam from the light source.

According to an embodiment of the present invention, in particular in connection to the door-like and double door-like embodiments described above, the gobos may be rigid, thereby being more robust and durable. The gobos may e.g. be made of hard plastic, metal or ceramics.

According to an embodiment of the present invention, a lighting system is provided. The lighting system may comprise a light source (such as a spotlight) arranged to emit a beam, and a gobo arrangement according to any one of the previously described embodiments. The gobo arrangement may be positioned such that the beam emitted by the light source is aimed at the light receiving region of the gobo arrangement. The present embodiment is advantageous in that a lighting system with a reduced size is provided, in particular, compared to a lighting system comprising a conventional gobo wheel. Further, the lighting system may provide several different light image projections.

In an embodiment, the light source may be a solid state light source and preferably an LED, which is advantageous in that it has improved energy efficiency, longer life time and the color of the light source may be changed electronically without moving parts.

In the present disclosure, the term "gobo holder" may refer to any means used for holding the gobos in relation to the rotational axis. For example, in particular in the case of rigid gobos, the gobo holder may constitute a portion of the gobo itself, which portion is arranged to rotate around the rotational axis. Further, it will be appreciated that the gobo holders may be supported by additional elements comprised in the gobo arrangement to form a stable structure.

Further objectives of, features of, and advantages with, the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described in the following.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiments of the present invention.

Figure 1 shows a lighting system comprising a conventional gobo wheel according to prior art technique.

Figure 2 shows a lighting system comprising a gobo arrangement according to an embodiment of the present invention.

Figure 3A shows a gobo arrangement according to another embodiment of the present invention, when a gobo is exposed in a light receiving region.

Figure 3B shows the gobo arrangement of Figure 3A, but when the gobo is pivoted out of the light receiving region.

Figure 4 shows a gobo arrangement according to yet another 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 the invention, wherein other parts may be omitted or merely suggested.

DETAILED DESCRIPTION

A lighting system with a conventional gobo wheel according to prior art technique will be described with reference to Figure 1.

A lighting system 1 comprises a spotlight 10 emitting a beam 160, a conventional gobo wheel 100 positioned in front of the spotlight 10, and a lens arrangement 150. The gobo wheel 100 comprises a circular plate 120, in which gobos 130 are

circumferentially arranged. The size of each gobo 130 essentially corresponds to the light output area of the spotlight 10 and the cross section area of the beam 160. The lighting system 1 is arranged such that the beam 160 from the spotlight 10 is aimed at the peripheral portion of the gobo wheel 100 where the gobos 130 are positioned, whereby the gobo 130 exposed in the beam 160 may be altered by rotating the gobo wheel 100. The size of the gobo wheel 100 is dependent on the number of gobos 130 and their size. Hence, the gobo wheel 100 may be rather large and impractical if a high number of gobos 130 are desired (such as five or more), and/or if the size of the gobos 130 have to be adapted to light sources with rather large light output area, such as halogen or LED based lamps. In particular, the gobo wheel 100 extends in the plane perpendicular to the direction of the beam 160, whereby the lighting system 1 is rather space taking between other spotlights.

A lighting system according to an embodiment of the present invention will be described with reference to Figure 2.

A lighting system 2 comprises a light source 20 emitting a beam 260. The light source 20 may preferably be a spotlight emitting a directional beam illuminating a limited, rather small area. For example, the light source 20 may be a HID lamp, a halogen lamp or an LED based lamp.

The lighting system further comprises a gobo arrangement 200 comprising a set of gobos 230. Each gobo 230 includes non-transparent portions 233 and transparent portions 234 together defining an image or pattern. Alternatively, or as a complement, the gobos 230 may comprise transparent portions of different colors to create an image or pattern. According to the present embodiment, the set of gobos 230 are formed by a flexible film (or foil). The gobos 230 are arranged side by side in a row along the flexible film. In other words, the film forms an elongated strip of gobos. The film may preferably be a flexible, plastic foil, which either may be transparent with printed non-transparent portions, or non-transparent with cut outs forming the transparent portions for defining the images or patterns of the gobos 230. The size of the gobos 230 may preferably match the size of the light output area of the light source 20 and/or the cross section area of the beam 260 at the location of the gobo arrangement 200 in relation to the light source 20. Alternatively, the gobos 230 may be smaller than the light output area of the light source 20.

The gobo arrangement 200 further comprises a first gobo holder 210 and a second gobo holder 220 for holding the set of gobos 230. Preferably, the gobo holders 210, 220 are formed by cylindrical elongated members having a length essentially corresponding to the width of the film with gobos 230. Further, the first gobo holder 210 is rotatable around a first rotational axis 211 and the second gobo holder 220 is rotatable around a second rotational axis 221 preferably parallel to the first rotational axis 211. The gobo holders 210, 220, as well as their rotational axes 211, 221, are spaced apart from each other and a light receiving region 240 spans between them. The gobo arrangement 200 is positioned such that the beam 260 of the light source 20 is aimed at the light receiving region 240. For example, the gobo arrangement 200 may be arranged straight in front of the light source 20 (as shown in Figure 2), or a mirror device may be arranged to reflect the beam 260 from the light source 20 onto the gobo arrangement 200 (not shown).

The elongated film strip with the set of gobos 230 is at one of its ends attached to and rolled up on the first gobo holder 210, and at its opposite end attached to and rolled up on the second gobo holder 220. As the first gobo holder 210 and the second gobo holder 220 (as well as their rotational axes 211, 221) are spaced apart, a portion of the film is stretched out between the gobo holders 210, 220 and thereby exposed in the light receiving region 240. The size of light receiving region 240 preferably corresponds to the size of one gobo 230, with a height corresponding to the height of one gobo 230 and a width corresponding to the width of one gobo 230 (and thus the width of the film).

Optionally, the lighting system 2 may comprise a lens arrangement 250 arranged to refract the beam 260 from the light source 20 in any appropriate way to provide the desired light projection image.

In the following, it will be described how the lighting system 2 operates to provide light projection images.

The light source 20 aims the beam 260 at the light receiving region 240 such that it is at least partly illuminated by the light source 20. Thus, the gobo 230 being exposed in the light receiving region 240 is illuminated by the light source 20 and shapes, by means of the transparent portions 234 and the non-transparent portions 233, the beam 260 according to the image or pattern of the gobo 230. The shaped beam is then refracted by the lens arrangement 250 and the image or pattern of the gobo 230 is projected at a remote surface, e.g. on a screen or stage about 2-20 m away from the lighting system 2.

When another gobo 230 is desired, the gobo holders 210, 220 are rotated around their rotational axes 211, 221, whereby the film is scrolled, until the other desired gobo 230 is exposed in the light receiving region 240. The gobo holders 210, 220 are rotated such that the film is rolled up on one of the gobo holders 210, 220 and simultaneously unrolled on the other. It will be appreciated that such scrolling of the film may be obtained either by rotating the gobo holders 210, 220 in the same direction (as will be the case in the embodiment shown in Figure 2) or in opposite directions, depending on which manner the film is rolled up on the gobo holders 210, 220. Further, scrolling of the film in one direction will be limited by the film being completely unrolled from one of the gobo holders 210, 220 and in the other direction when the film is completely unrolled from the other one of the gobo holders 210, 220.

A gobo arrangement according to another embodiment of the present invention will be described with reference to Figures 3 A and 3B.

A gobo arrangement 300 comprises a set of gobos 330 (for the sake of clarity, merely one gobo 330 is shown in Figures 3 A and 3B). The gobos 330 comprise non- transparent portions 333 and transparent portions 334 for shaping a beam from a light source (in similarity with the gobos in the embodiment of Figure 2). The gobos 330 are preferably made in a rigid non-transparent material, such as plastic or metal, in which the transparent portions 334 are formed of cut outs. Alternatively, the gobos 330 may be made of a flexible foil (in similarity with the gobos in the embodiment of Figure 2) fixed in a rigid frame, or in transparent rigid plastic or ceramics, such as glass, on which the non-transparent portions 333 are printed. Further, in the present embodiment, each gobo 330 is divided into a first piece 331 and a second piece 332. Preferably, the dividing is arranged essentially through the centre of the gobo 330 such that the gobo pieces 331, 332 are of about the same size.

The first piece 331 of the gobo 330 is attached to a first gobo holder 310, which is rotatable around a first rotational axis 311, and the second piece 332 of the gobo 330 is attached to a second gobo holder 320, which is rotatable around a second rotational axis 321, whereby the gobo pieces 331, 332 are allowed to pivot around the rotational axis 311, 312 of the gobo holder 310, 320 they are attached to. The gobo holders 310, 320 are spaced apart by a distance corresponding to the width of the gobo 330 such that the two pieces 331, 332 are allowed to mate between the gobo holders 310, 320 (as shown in Figure 3A). A light receiving region 340 spans between the rotational axes 310, 320, and is adapted to be illuminated by a light source.

When a certain gobo 330 is to be used for light projection, the pieces 331, 332 of that gobo 330 are pivoted into the light receiving region 340 such that they mate and provides the complete gobo 330 and are exposed in the light receiving region 340 (as shown in Figure 3A). When it is desired to alter the gobo exposed in the light receiving region 340 (as well as if it is desired not to use any gobo), the pieces 331, 332 of the currently exposed gobo 330 are pivoted out of the light receiving region 340, preferably by a pivoting angle of at least 90° (as shown in Figure 3B) for avoiding blocking the light beam. Meanwhile, or subsequently, another gobo may be pivoted into the light receiving region 340.

The principle of a gobo arrangement according to another embodiment of the present invention will be described with reference to Figure 4.

A gobo arrangement 400 comprises a set of gobos 430 similar to the gobos described with reference to Figures 3 A and 3B, except that they are not divided into two pieces, but instead formed by single pieces. The gobo arrangement 400 further comprises a first gobo holder 420 rotatable around a first rotational axis 411 and a second gobo holder 420 rotatable around a second rotational axis 421. The gobo holders 410, 420 are arranged in similarity with the gobo holders described with reference to Figures 3 A and 3B, with a light receiving region 440 spanning between them.

In the present embodiment, each gobo 430 is attached to one of the gobo holders 410, 420 such that each gobo 430 is allowed to pivot into and out of the light receiving region 440 by pivoting around the rotational axis 411, 421 of the gobo holder 410, 420 it is attached to.

In similarity with the embodiment described with reference to Figures 3A and

3B, the gobo 430 to be used for light projection is pivoted into the light receiving region 440 and may hence be exposed to a beam from a light source. When another gobo 430 is desired for light projection, the currently exposed gobo 430 is pivoted out of the light receiving region 440, and another gobo 430 may be pivoted into the light receiving region 440.

Preferably, the gobo arrangement may comprise means for blocking the gobos

430 to pivot more than about 90° from the light receiving region 440, whereby the gobo arrangement 400 requires a reduced space laterally. Such blocking means may be provided in any of the above described embodiments. In the following, embodiments combinable with any or some of the previously described embodiments will be described.

The gobo holders may be rotated by any electromechanical means, such as an electric motor, or manually. With reference to the door-like embodiments described with reference to Figures 3A, 3B and 4, the gobos may be individually movable and controllable to pivot into and out of the light receiving region.

Further, the gobo holders may be shaped as elongated members or, in particular with reference to the door-like embodiments described with reference to Figures 3A, 3B and 4, in any suitable way for holding the gobos and rotate them around the rotational axes.

Furthermore, the gobo arrangement may comprise means for mounting it to a light source.

Optionally, the gobo arrangement may comprise one or more color filters 435, as exemplified in Figure 4.

The person skilled in the art realizes that the present invention by no means is limited to the embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. In particular, each one of the embodiments described with reference to Figures 2-4 (the scroll embodiment, and the pivot embodiments, respectively) may be combined with each other in any appropriate way. In particular, the gobo arrangements described with reference to Figures 3A, 3B and 4 may be used in a lighting system as described in Figure 2. Further, the gobo design described with reference to Figure 2 may be used in the embodiments described with reference to Figures 3A, 3B and 4.

Claims

CLAIMS:

1. A gobo arrangement (200, 300, 400) comprising:

a first gobo holder (210, 310, 410) arranged to rotate around a first rotational axis (211, 311, 411),

a second gobo holder (220, 320, 420) arranged to rotate around a second rotational axis (221, 321, 421) spaced apart from the first rotational axis,

a light receiving region (240, 340, 440) spanning between the first and second rotational axes, the light receiving region being adapted to be at least partly illuminated by a light source (20), and

a set of at least two gobos (230, 330, 430), each gobo mounted to the first and/or the second gobo holder such that each one of the gobos is allowed to be exposed in the light receiving region.

2. A gobo arrangement as defined in claim 1, wherein a gobo of the set of gobos comprises portions having different luminous transmittance.

3. A gobo arrangement as defined in claim 1, wherein the size of the light receiving region matches the size of one gobo of the set of gobos.

4. A gobo arrangement as defined in claim 1, wherein the gobos are made of plastic.

5. A gobo arrangement as defined in claim 1, wherein the set of gobos comprises more than two gobos.

6. A gobo arrangement as defined in claim 1, wherein the gobos are arranged side by side at a flexible film, which at one of its ends is attached to and rolled up on the first gobo holder and at the opposite end is attached to and rolled up on the second gobo holder.

7. A gobo arrangement as defined in claim 6, wherein the film is arranged to be rolled up on one of the first and second gobo holders simultaneously as it is unrolled on the other one of the first and second gobo holders upon alternation of the gobo exposed in the light receiving region.

8. A gobo arrangement as defined in claim 1, wherein the first gobo holder is formed by a first elongated, preferably cylindrical, member and the second gobo holder is formed by a second elongated, preferably cylindrical, member.

9. A gobo arrangement as defined in claim 1, wherein each one of the gobos is attached to one of the gobo holders such that each gobo is pivotally movable around the rotational axis of the gobo holder it is attached to.

10. A gobo arrangement as defined in claim 9, wherein at least two gobos are attached to one of the first and second gobo holders such that they are pivotally movable around the rotational axis of the gobo holder they are attached to, and preferably controllable, independently of each other.

11. A gobo arrangement as defined in claim 1, wherein each one of the gobos is divided into two pieces (331, 332), wherein one of the two pieces is attached to the first gobo holder and the other piece is attached to the second gobo holder, wherein each one of the pieces is pivotally movable around the rotational axis of the gobo holder it is attached to such that the two pieces are allowed to mate in the light receiving region.

12. A gobo arrangement as defined in claim 11, wherein the pieces of the gobos being attached to the one and the same gobo holder are pivotally movable around the rotational axis of the gobo holder they are attached to, and preferably controllable, independently of each other.

13. A gobo arrangement as defined in claim 9 or 11, wherein the gobos are rigid.

14. A lighting system (2) comprising:

a light source (20) arranged to emit a beam, and

a gobo arrangement (200, 300, 400) as defined in claim 1, wherein the gobo arrangement is positioned such that the beam (260) emitted by the light source is aimed at the light receiving region (240, 340, 440) of the gobo arrangement.

15. A lighting system as defined in claim 14, wherein the light source is a solid state light source and preferably a light emitting diode.