VAN ZON, Fokke (AE Eindhoven, NL-5656, NL)
TUKKER, Teunis, Willem (AE Eindhoven, NL-5656, NL)
KURT, Ralph (AE Eindhoven, NL-5656, NL)
SIPKES, Mark, Eduard, Johan (AE Eindhoven, NL-5656, NL)
ANSEMS, Johannes, Petrus, Maria (AE Eindhoven, NL-5656, NL)
VAN GORKOM, Ramon, Pascal (AE Eindhoven, NL-5656, NL)
VAN ZON, Fokke (AE Eindhoven, NL-5656, NL)
TUKKER, Teunis, Willem (AE Eindhoven, NL-5656, NL)
KURT, Ralph (AE Eindhoven, NL-5656, NL)
SIPKES, Mark, Eduard, Johan (AE Eindhoven, NL-5656, NL)
ANSEMS, Johannes, Petrus, Maria (AE Eindhoven, NL-5656, NL)
| CLAIMS: 1. A lighting device (1) for providing a variable light-beam, said lighting device comprising: a light source (2); a first lens array (5) including a first plurality of positive lenses (6), said first lens array (5) being arranged to receive light from said light source (2); a second lens array (12) arranged to receive light having passed through said first lens array (5), said second lens array including a second plurality of lenses (13), each being aligned with a corresponding one of said positive lenses in said first plurality of positive lenses in the first lens array (5); and a light-modifying element (7, 8, 9, 10) being arranged between said first lens array (5) and said second lens array (12), wherein said lighting device (2) is configured in such a way that an optical distance between said first lens array (5) and said second lens array (12) can be varied; and wherein said light-modifying element (7, 8, 9, 10) is configured to allow modification of light propagation properties in each space between one of said lenses in said second plurality of lenses in the second lens array (12), and said corresponding one of said positive lenses in said first plurality of positive lenses in the first lens array (5). 2. A lighting device (1) according to claim 1, comprising a plurality of light- sources (2). 3. A lighting device (1) according to claim 1 or 2, comprising at least one light emitting diode. 4. A lighting device (1) according to any one of the preceding claims, wherein said light-modifying element comprises at least one movable mask (7, 8, 9, 10) having a plurality of openings (11), each of said openings being arranged between one of said positive lenses (6) in said first plurality of positive lenses in the first lens array (5), and a corresponding one of said lenses (13) in said second plurality of lenses in the second lens array (12). 5. A lighting device (1) according to claim 4, wherein said light-modifying element comprises a plurality of individually movable masks (7, 8, 9, 10). 6. A lighting device (1) according to claim 5, wherein said plurality of individually movable masks comprises at least four individually movable masks (7, 8, 9, 10). 7. A lighting device (1) according to any one of the preceding claims, wherein said light-modifying element is configured in such a way that an optical distance between said light-modifying element (7, 8, 9, 10) and said first lens array (5) can be varied. 8. A lighting device (1) according to any one of the preceding claims, wherein said second plurality of lenses (13) are positive lenses. 9. A lighting device (1) according to any one of the preceding claims, further comprising a collimator (4) arranged between said light source (2) and said first lens array (5). 10. A lighting device (1) according to claim 9, comprising a plurality of collimators, each being arranged between one of a corresponding plurality of light sources in said light source array and one of a corresponding plurality of first positive lens in said first lens array. 11. A lighting device (1) according to claim 9 or 10, further comprising a lens arranged between said collimator and said first lens array. 12. A lighting device (1) according to claim 11, comprising a plurality of lenses arranged in a lens array arranged between said collimator and said first lens array. 13. A lighting device (1) according to any one of the preceding claims, wherein at least one of said positive lenses in said first plurality of positive lenses in the first lens array are Fresnel lenses. A lighting device (1) according to any one of the preceding claims, wherein atd lenses in said second plurality of lenses in the second lens array are Fresnel |
TECHNICAL FIELD
The present invention relates to a lighting device for providing a variable light-beam. BACKGROUND OF THE INVENTION
In lighting fixtures for entertainment lighting used for example in theatres, stages or TV studios the possibility of varying the light beam is needed. For this purpose, lighting systems using halogen light sources have been used to a great extent. One important feature of such lighting systems is the zoom function, which is used to attract attention to a specific point during for example a theatre show by illuminating that point with a tightly focused light. In addition, it is also often desirable to provide for illumination of a wide area with diffuse light. These lighting systems are often provided with a bulky lens arrangement for zoom functionality.
A solution to the problem of the space consuming lens arrangements typically used in the above-mentioned lighting systems is described in WO2005/093319, which discloses a floodlight comprising means for generating a convergent beam. In the device disclosed by WO2005/093319, two lenses are located around the central axis thereof, and by moving the second lens along the central axis, the beam is changed. By moving the lens perpendicularly to the central axis, the angle of the beam may be changed. Although WO2005/093319 provides a floodlight which can provide various beams, there is room for improvement. In particular there is room for improvement regarding the possibility of controlling the shape of the beam.
SUMMARY OF THE INVENTION
In view of the above, a general object of the present invention is to provide an improved lighting device, in particular enabling improved control of the spatial intensity distribution of the light-beam provided by the lighting device.
According to a first aspect of the invention, there is provided a lighting device for providing a variable light-beam, the lighting device comprising a light source; a first lens array including a first plurality of positive lenses, the first lens array being arranged to receive light from the light source; a second lens array arranged to receive light having passed through the first lens array, the second lens array including a second plurality of lenses, each being aligned with a corresponding one of the positive lenses in the first plurality of positive lenses in the first lens array; and a light-modifying element being arranged between the first lens array and the second lens array, wherein the lighting device is configured in such a way that an optical distance between the first lens array and the second lens array can be varied; and wherein the light-modifying element is configured to allow modification of light propagation properties in each space between one of the lenses in the second plurality of lenses in the second lens array, and the corresponding one of the positive lenses in the first plurality of positive lenses in the first lens array.
By "optical distance" should, in the context of the present application, be understood as a distance along an optical axis of the lighting device, on which the light propagates. The first lens array, second lens array, collimators etc. are all arranged along the optical axis and may impact the optical distance by collimating or refracting the light. The optical distance may also be different from a physical distance between the first lens array and the second lens array.
The optical distance can be varied in various ways. For example, it could be varied by inserting a medium with a different refractive index between the first lens array and the second lens array. The optical distance could thus be changed without moving the first lens array or the second lens array.
In the context of the present invention the "light-modifying element" is to be understood as an object capable of at least partly blocking or absorbing light, thus preventing one or several optical paths along the optical axis. The light-modifying element may also be arranged in way that it refracts the light or guides the light from the first lens array in such way that a fraction of the light having passed through the first lens array does not reach the second lens array. The refracted or guided light could for example be recycled and reused in the lighting device.
The present invention is based on the realization that light along the optical axis can be modified in various ways, for example completely or partially blocked or refracted to achieve an output having an improved combination of zoom and so-called barn door functionality.
The term "barn door functionality" should, in the context of the present application, be understood as the effect of shaping an output light beam wherein light is partially or completely blocked in a direction towards a predetermined area. Traditionally, the barn door functionality is achieved by using so-called barn doors, such as metal flaps or similar, arranged circumferentially around the output of a lighting device. By moving one or several of the barn doors into the light beam, the light could be partially or completely blocked, thereby achieving a variably shaped light beam.
In the present invention a light-modifying element is arranged between the first lens array and the second lens array. The light-modifying element can be controlled to partially or completely block light between the first lens array and the second lens array. The shape of the output light beam is then varied, depending on the actual position of the light- modifying element and the amount of light being blocked.
The result is an improved lighting device, which is more compact in size than prior art devices. For example, the lighting device according to various embodiments of the invention requires no externally mounted flaps to achieve the above-described barn door functionality.
Advantageously, the light-modifying element may be configured to modify the light propagation properties in each space in substantially the same way in response to a user request.
According to various embodiments of the present invention, the lighting device may comprise a plurality of light-sources.
Advantageously, furthermore, the lighting device may comprise at least one light emitting diode (LED) and/or LED-assembly. A LED-assembly may include one or more LEDs.
Using LEDs or other solid state light-sources instead of for example a halogen light source reduces the amount of heat generated since LEDs generate virtually no heat. In addition LEDs allow for a color controllable output of the lighting device without using color filters, thus reducing light losses in a system. The efficiency in a system operated with LEDs is also increased due to the low power consumption of LEDs.
According to an embodiment of the invention the light-modifying element comprises at least one movable mask having a plurality of openings, each of the openings being arranged between one of said positive lenses in said first plurality of positive lenses in the first lens array, and a corresponding one of said lenses in said second plurality of lenses in the second lens array. Using the movable mask, light can conveniently be blocked between the first lens array and the second lens array to achieve the barn door functionality at the output of the device.
The light-modifying element may comprise a plurality of individually movable masks. Each individually movable masks is capable of partially or completely block light between the first lens array and the second lens array to achieve the above described barn door functionality. In yet another embodiment the individually movable masks may comprise at least four individually movable masks.
By moving the individually movable masks, they may be controlled to either let all the light pass through or block part the light from reaching the second lens array. Each of the four individually movable masks could be moved in any direction between the first lens array and the second lens array. If the masks are aligned such that all light is let through, then by moving one or several of the masks, for example, upwards, the light going downwards between the first lens array and the second lens array will be blocked. The output light beam will then be directed mainly downwards.
Similarly the light going upwards is blocked when the masks are moved downwards, thus directing the output light beam mainly upwards. The same phenomena occur if the masks are moved in a left or right direction.
Overall, by using individually movable masks, the barn door functionality and the shaping of the beam may be improved compared to lighting devices equipped with conventional barn doors using flaps.
Furthermore, the light-modifying element may be configured in such a way that an optical distance between said light-modifying element and said first lens array can be varied.
By moving the light-modifying element away from/towards the first lens array, and thus simultaneously correspondingly towards/ away from the second lens array, the output shape of the beam can be sharpened or less sharpened.
According to various embodiments of the invention, the second plurality of lenses may be positive lenses.
By using positive lenses in both the first lens array and the second lens array, the light will have focal points that may be achieved at a fixed distance between the first lens array and the second lens array. This configuration facilitates the design of the lighting device and/or control of the light-modifying element, since control of the beam can be achieved with only small variations in the configuration of the light-modifying element. According to an embodiment of the invention, the lighting device may further comprise a collimator arranged between said light source array and said first lens array.
According to yet another embodiment of the present invention, the lighting device may comprise a plurality of collimators, each being arranged between one of a corresponding plurality of light sources in said light source array and one of a corresponding plurality of first positive lens in said first lens array.
Arranging collimators between the light source and the first lens array is used to generate a parallel beam of light entering the first lens array and to make sure that as much light as possible emitted from the light source, is received by the first lens array.
In another embodiment according to the present invention, the lighting device may further comprise a lens arranged between the collimator and the first lens array.
The advantage of using a lens at the output of the collimator or collimators is that the distance between the first lens array and second lens array can be further reduced.
Moreover, some or all of the lenses in the first and/or second lens arrays can be provided in the form of Fresnel lenses.
Using Fresnel lenses could make the system lighter.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing an exemplary embodiment of the invention, wherein:
Fig.l is a perspective view of a lighting device according to a preferred embodiment of the present invention;
Figs. 2a-b schematically illustrate a zoom function in the lighting device in Fig. 1; and
Fig. 2c schematically illustrates a barn door function in the lighting device in
Fig. 1.
DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION
In the following description, the present invention is described with reference to a lighting device comprising a first lens array with positive lenses and a second lens array with positive lenses. Between the first lens array and the second lens array, four individually movable masks are arranged. Each of these masks has a plurality of rectangular openings, each being arranged to allow control of light propagating between a lens in the first lens array and a corresponding lens in the second lens array. Furthermore, the lighting device comprises a LED-array for providing the light.
It should be noted that this by no means limits the scope of the invention, which is equally applicable to lighting devices in which the second lens array comprises a plurality of negative lenses. Furthermore, the light-modifying element may, for example, comprise a smaller or larger number of individually moving masks, and the masks can have openings that are not rectangular. For example, the openings may be circular. Moreover, the light may be emitted by a single light-source, such as a single halogen lamp.
Fig. 1 illustrates a lighting device 1 according to an embodiment of the present invention. The lighting device 1 comprises a light source array formed by multiple light sources, such as a LED array 2, mounted on a base 3. The LED-array 2, which is arranged to emit light into a collimator 4 is used to generate light with a specific intensity and color. The lighting device 1 further includes a first lens array 5 having a plurality of lenses 6 and being arranged to receive light from the LED array 2. As can be seen in Fig.1 the collimator 4 is arranged such that light from the LED array 2 is collimated and guided into the first lens array 5.
The lighting device 1 further includes a plurality of individually movable masks and in a preferred embodiment four individually movable masks 7, 8, 9, 10 are used as illustrated in Fig. 1. Each mask 7, 8, 9, 10 is movable in an up/down or left/right or frontwards/backwards direction. Each individual mask comprises a plurality of openings 11 , wherein each opening 11 may be arranged in front of a corresponding lens 6 in the first lens array 5.
A second lens array 12 having a plurality of lenses 13 is arranged in front of the individually movable masks 7, 8, 9, 10. Each lens 13 in the second lens array 12 may also be arranged in front of a corresponding opening 11 in the individually movable masks 7, 8, 9, 10.
The masks 7, 8, 9, 10 act as light-modifying elements capable of partially or completely blocking or absorbing light to provide barn door functionality. Although the masks 7, 8, 9, 10 are movable in three dimensions, a lens 6 in the first lens array 5 and a lens 13 in the second lens array 12 are arranged in front of each other in a preferred embodiment of the invention.
The masks 7, 8, 9, 10 comprise means for moving each mask 7, 8, 9, 10. The means for moving masks are illustrated in Fig. 1 as grooves 14, 15 and protrusions 16, 17. The first lens array 5 and the second lens array 12 comprises means, which are not shown in the figures, for moving the lens arrays 5, 12 either frontwards or backwards in relation to each other to provide a zoom function.
In Fig. 2a, the light propagation through one lens 6 in the first lens array 5 and one lens 13 in the second lens array 12 is illustrated using a couple of paths whereon the light may travel. For the purpose of providing a better understanding of the function of an embodiment according to the present invention, only a few pairs of lenses 6, 13, having propagation paths are shown. A lens 6, 13 should thus not be limited to a single lens and could refer to a plurality of lenses according to a preferred embodiment. Additional lenses 6, 13 in the first lens array 5 and the second lens array 12 exhibit the same phenomena. The light source is not shown although the light originates from the light source and is received by a lens 6 in the first lens array 5, which lens 6 is shown to the left in Fig. 2a.
Correspondingly a second lens 13 in the second lens array 12 is shown to the right in Fig 2a. The light received by the first lens 6 is refracted before it is received by the second lens 13.
In the configuration shown in Fig. 2a, the first lens 6 and the second lens 13 are separated with a distance such that an intermediate focus is achieved between the lenses 6, 13. After the focus point, the light begins to diverge before being received by the second lens 13. In the second lens 13, the light is again refracted in order to provide an output light beam.
Fig 2b. illustrates a configuration in which the second lens array 13 has been moved towards the first lens array 5 as compared to the situation in Fig. 2a, such that a lens in the second lens array 12 is positioned adjacent to or on the focus point generated from the first lens. The light will in this case not be as diverged as in the configuration shown in Fig. 2a. when the light is received by the lens 13 in the second lens array 12.
The effect achieved is that the refraction within the lens 13 in the second lens array 12 will provide an output light beam having a wider divergent beam compared to the configuration shown in Fig. 2a. Thus, by moving the second lens array 12 frontwards and backwards a zoom function is achieved, wherein one configuration may provide a concentrated beam illuminating a specific area and another configuration may spread out the light in a much wider area.
Fig 2c. shows an embodiment according to the present invention comprising the first lens array 5, the second lens array 12 and an individually movable mask 7, 8, 9, 10. For ease of drawings only a single movable mask is shown in Fig. 2c, which mask is used to illustrate how a barn-door effect may be achieved on the output light beam. The individually movable mask 7, 8, 9, 10 is moved downwards to a position wherein it blocks parts of the upwards going light from the first lens array 5 that should have reached the second lens array 12. The effect is that the output light beam will have a varying shape depending on which part of the light is blocked between the first lens array 5 and the second lens array 12. It is illustrated in Fig. 2c with an output beam being tilted slightly upwards.
Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. For example, the lighting device 1 is not limited to the use of LEDs. In fact, various other types of light sources may be used, such as an incandescent lamp, a laser, an organic light emitting diode (OLED), a gas discharge lamp, a fluorescent lamp (TL).
In the 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 measured cannot be used to advantage.