ILLUMINATION SYSTEM

FIELD OF THE INVENTION

The present invention relates to an illumination system that comprises illumination means for producing an illumination beam and means for changing the vergence of said illumination beam.

The invention is particularly relevant for lighting such as stage lighting or shop lighting.

BACKGROUND OF THE INVENTION

An illumination system that comprises illumination means for producing an illumination beam and means for changing the vergence of said illumination beam is known from patent US 4,855,884. This illumination system comprises a lamp mounted at the centre of a reflector. A motor provides rotation of a lead screw that acts on the reflector, thus providing displacement of said reflector. Displacement of the reflector results in a modification of the reflector curvature and the width or vergence of the beam issuing from the reflector is therefore affected. Typically, a plurality of such illumination systems is suspended from a truss by a gimbal. The illumination systems may then be controlled separately or as a unit to tilt or to pan. When a particular object has to be enlightened, for example an object located on the front of the stage, the illumination system is directed towards said object and the vergence of the illumination beam is adjusted so as to suitably enlighten said object. Then, when another object has to be enlightened, for example an object located on the back of the stage, the illumination system is directed towards said object and the vergence of the illumination beam is adjusted so as to suitably enlighten said object. Hence, use of this illumination system is complicated, as the operator has to perform many operations in order to be able to suitably enlighten different objects. A relatively long time is thus required when switching from one object to another.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an illumination system that can produce a variable vergence illumination beam, wherein the use of said illumination system is facilitated.

To this end, the invention proposes an illumination system comprising first illumination means for producing a first illumination beam and first means for changing the vergence of said first illumination beam, said first illumination means and said first changing means being located along a first optical axis, said illumination system further comprising first means for converting a movement of said first optical axis into a change of vergence of said first illumination beam.

According to the invention, a change of the direction or position of the illumination beam leads to a change of the vergence of the illumination beam. As a consequence, when an object has to be enlightened, an operator adjusts the position of the illumination system, and the vergence of the illumination beam is automatically adjusted. This means that a single operation has to be performed; hence the use of the illumination system is facilitated.

Advantageously, the illumination system further comprises second illumination means for producing a second illumination beam and second means for changing the vergence of said second illumination beam, said second illumination means and said second changing means being located along a second optical axis, second means for converting a movement of said second optical axis into a change of vergence of said second illumination beam and third means for converting a movement of said first optical axis into a movement of said second optical axis.

This advantageous embodiment relates to an illumination system that comprises a plurality of units, each providing an illumination beam. According to this advantageous embodiment, an operator only needs to move one of the units, and all the units will accordingly be moved, and the vergences of all the beams will accordingly be adjusted. Such an illumination system is thus particularly easy to use.

Preferably, the first, second and third converting means are arranged in such a way that a movement of the first optical axis leads to an identical change of vergence of the first and second illumination beams. In this case, all the illumination beams may have the same vergence and thus the same intensity when the illumination system is moved. This makes use of the illumination system relatively easy, because one can rely on the adjustment of only one unit. In a first configuration, the first converting means comprise means for converting a rotation of said optical axis into a relative translation of said changing means with respect to said illumination means. The first converting means may comprise, for instance, a rack-and- pinion gear.

In a second configuration, the first converting means comprise means for converting a translation of said optical axis into a relative translation of said changing means with respect to said illumination means. The first converting means may comprise, for instance, a rack- and-pinion gear. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail by way of example with reference to the accompanying drawings, in which :

- Figs. Ia and Ib show an illumination system according to a first configuration of the invention, in a first position and Figs. Ic and Id show the illumination system of Figs. Ia and Ib, in a second position ;

- Fig. 2 shows the illumination system of Fig. Ia and Ib in an advantageous embodiment of the invention;

- Figs. 3a and 3b diagrammatically show the third converting means of the illumination system of Fig. 2;

- Figs. 4a and 4b show an illumination system according to a second configuration of the invention, in an advantageous embodiment of the invention, in a first position; - Figs. 5a and 5b show the illumination system of Figs. 4a and 4b in a second position;

- Fig. 6 shows in detail the first converting means of the illumination system of Figs. 4a and 4b.

DETAILED DESCRIPTION OF THE INVENTION Fig. Ia shows an illumination system according to a first configuration of the invention. The illumination system is supported by a support 10. The illumination system comprises an optical unit 11 and converting means 12. Fig. Ib diagrammatically shows the optical unit 11 of Fig. Ia. The optical unit 11 comprises illumination means 111 and changing means 112. The illumination means 111 are adapted for producing an illumination beam IB. The illumination means and the changing means 112 are located along an optical axis AA. The changing means comprise a lens that is movable along the optical axis AA. The movable lens forms means for changing the vergence of the illumination beam IB. Actually, when the illumination means 111 are placed at the focal point of the lens, as is the case in Fig. Id, the illumination beam IB is a parallel beam, whereas when the illumination

means 111 are located closer to the lens, as is the case in Fig. Ib, the illumination beam IB is a diverging beam.

The illumination means 111 may comprise a radiation source, such as a lamp or a LED. The illumination means may also comprise a plurality of radiation sources, such as an array of LEDs. A plurality of radiation sources produce a plurality of individual beams, and the combination of all the individual beams form the illumination beam.

The means for changing the vergence of the illumination beam may have other forms than a movable lens. For example, a movable and deformable reflector, such as the reflector of US 4,855,884, may be used. The converting means 12 are adapted for converting a movement of the optical axis

AA into a change of vergence of the illumination beam IB. In this example, the converting means 12 comprise a pinion attached to the support 10, and a rack attached to the movable lens 112. When the optical unit 11 is rotated around the axis of rotation of the pinion, the optical axis AA is rotated with respect to the support 10. The rack is translated along a direction parallel to the optical axis AA by means of the rack-and-pinion gear. As a consequence, the movable lens is moved along the optical axis AA and the vergence of the illumination beam IB is changed.

Instead of a rack-and-pinion gear, other converting means 12 may be used. In the first configuration of the invention, the converting means 12 are adapted for converting a rotation of the optical axis AA into a relative translation of the changing means 112 with respect to the illumination means 111. For instance, a cam system may be used as converting means 12.

Although, in the preceding example, the rack is attached to the changing means 112, the rack may instead be attached to the illumination means 111, because only a relative translation of the changing means 112 with respect to the illumination means 111 is required in order to change the vergence of the illumination beam IB.

In the first position depicted in Figs. Ia and Ib, the illumination beam IB is a diverging beam. The optical axis AA, which defines the mean direction of the illumination beam IB, has a first position with respect to the support 10. The illumination system of Figs. Ia to Id may for instance be placed above the front of a stage. In the first position of Figs. Ia and Ib, the illumination system is used for enlightening the back of the stage. In this case, a large illumination beam may be needed, for example if large objects are placed at the back of the stage. In the second position depicted in Fig. Ic and Id, the illumination beam IB is a parallel beam. In this second position, the illumination system is used for enlightening the front of the stage. In this case, a small and intense illumination beam may be needed, for

example if small objects or an actress is placed at the front of the stage. Of course, the change of vergence of the illumination beam IB as a function of its position or direction may be adjusted, depending on the required use of the illumination system. It is possible, for instance, to design the converting means 12 and the changing means 112 in such a way that the illumination beam IB becomes larger and larger when one goes from the back to the front of the stage. Once the illumination system has been properly designed, its use is relatively easy because an operator only has to position the optical unit 11 towards the desired direction, and the vergence of the illumination beam is automatically changed.

Fig. 2 shows the illumination system of Figs. Ia and Ib in an advantageous embodiment of the invention. This illumination system comprises the first optical unit 11 and the first converting means 12 depicted in Figs. Ia to Id. It also comprises a second optical unit 21 and second converting means 22, which are identical to the first optical unit 11 and the first converting means 12. The first optical unit 11 comprises the first illumination means 111 and the first changing means 112 located along the first optical axis AA, as depicted in Fig. Ib. The second optical unit comprises second illumination means for producing a second illumination beam and second means for changing the vergence of said second illumination beam, and these second illumination means and second changing means are located along a second optical axis BB. The illumination system of Fig. 2 further comprises third converting means 23 for converting a movement of the first optical axis AA into a movement of the second optical axis BB.

When a rotation of the first optical axis AA is performed, this rotation is converted into a change of the vergence of the first illumination beam, as has been described in Figs. Ia to Id. In the same time, the rotation of the first optical unit 11 leads to a rotation of the second optical unit 21, by means of the third converting means 23, which are described in more details in Figs. 3a and 3b. As the second optical axis BB is rotated, the vergence of the second illumination beam is changed by means of the second converting means 22. In the example of Fig. 2, the first and second converting means 12 and 22 are identical, which means that the changes of vergence of the first and second illumination beams are identical. However, the illumination system may be designed in such a way that different changes of vergence are achieved, for example in that different rack-and pinion gears are chosen for the first and second converting means 12 and 22. It may however be advantageous that a movement of the first optical axis AA leads to a same change of vergence of the first and

second illumination beams, as in this case any optical unit can be moved for adjusting the optical system, because the result on all the illumination beams will be the same.

The illumination system of Fig. 2 further comprises a third optical unit, which is identical to the first and second optical units 11 and 21. The illumination system may comprise any number of optical units. Preferably, the illumination system comprises a ring of optical units, i.e. the support 10 has the shape of a ring and an appropriate number of optical units is disposed around said ring. This is particularly advantageous for obtaining circular light beams with variable diameters. Actually, a small circular light beam may be obtained by focusing all the illumination beams towards a same point, which is located at the vertical of the center of the ring support 10. In order to increase the diameter of the light beam, the optical units are rotated. If the size of each illumination beam remained the same during said rotation, a plurality of individual light beams would be created, hence a ring of light beams would be created instead of an homogenous circular light beam. Thanks to the invention, the rotation of the optical units increases the diameter of each illumination beam, which makes it possible to obtain a circular homogeneous light beam. As a consequence, an operator may change the size of a circular light beam obtained by means of such a ring illumination system, only in that one of the optical units is rotated. This makes use of such an illumination system relatively easy.

Figs. 3a and 3b diagrammatically show the third converting means 23 of Fig. 2. In

Figs. 3a and 3b, the optical units such as the first optical unit 11 and the second optical unit 21 are shown only diagrammatically. As can be seen from Figs. 3a and 3b, the support 10 cannot be deformed, whereas the third converting means 23 can be deformed. The third converting means 23 comprise, in this example, an annular spring or portions of annular spring. When the first optical unit 11 is rotated with respect to the support 10, the portion of the annular spring located between the first and second optical units 11 and 21 is deformed. This leads to a rotation of the second optical unit 21. This in turn leads to a deformation of the portion of the annular spring located between the second optical unit 21 and its adjacent optical unit, and so on. Hence the rotation of a single optical unit leads to a same rotation of all the optical units of the ring. Between Fig. 3 a and Fig. 3b, it can be seen that the positions of all the optical units with respect to the support 10 have been identically changed.

An illumination system according to a second configuration of the invention is depicted in Figs. 4a, 4b, 5a, 5b and 6. Fig. 4a is a side view and Fig. 4b is a perspective view

of this illumination system in a first position. Fig. 5a is a side view and Fig. 5b is a perspective view of this illumination system in a second position. Fig. 6 is a detailed perspective view of a part of this illumination system.

The illumination system comprises first and second optical units 11 and 21, first and second converting means 12 and 22 and third converting means 23. The third converting means 23 comprise portions of spring between two adjacent optical units. For example, a single spring may be used, the optical units being fixed to certain turns of the spring. One of the extremities of the spring is fixed to a fix point, the other one is fixed to a point that can be moved between at least a first and a second position. A blocking system that can be moved with respect to the fixed point and then be locked in a fixed position may be used for that purpose. This blocking system may be attached to one of the optical units, which is the most remove optical unit from the fixed point. In the first position, the illumination system is in the first position of Figs. 4a and 4b, where the spring is pressed, and in the second position the illumination system is in the position of Figs. 5a and 5b, where the spring is less pressed. The distance between two adjacent optical units is changed from the position of Figs. 4a and 4b to the second position of Figs. 5a and 5b, but the distances between two adjacent optical units of the illumination system in a given position are all equal.

As can be seen from Fig. 6, which show the second optical unit 21 and the second converting means 22, the converting means 22 comprise a rack 221 and a pinion 222 and the second optical unit 21 comprises second changing means 212. Illumination means 211 are not shown, but are fixed along the optical axis BB, i.e. they cannot be translated along the optical axis BB. The changing means 212 comprise a thread and the pinion is mounted on the thread in such a way that a rotation of the pinion 222 leads to a translation of the changing means 212. Hence a rotation of the pinion 222 leads to a change of the vergence of the illumination beam produced by the second optical unit 21. One end of the rack 221 is attached to the first optical unit 11, as can be seen from Figs. 4a to 5b.

When the distance between the first and the second optical unit 11 and 21 is increased, the pinion 222 is rotated because the length of the rack 221 is constant. As a consequence, the changing means 212 are translated along the second optical axis BB and the vergence of the second illumination beam is changed. As an increase of the distance between the first and the second optical unit 11 and 21 also implies an increase of the distance between the second optical unit 21 and the next adjacent optical unit, the vergence of the beam produced by said next adjacent optical unit is changed in the same way.

It should be noted that the pinion of the first converting means 12 is combined with a rack, which is not shown but which end is attached to the fixed point, such as the support of the illumination system. In this way, the displacement of the first optical unit 11 leads to a same change of vergence of the illumination beam produced by said first optical unit 11.

Instead of a rack-and-pinion gear, other converting means 12 or 22 may be used. In the second configuration of the invention, the converting means 12 or 22 are adapted for converting a translation of the optical axis AA or BB into a relative translation of the changing means 112 or 212 with respect to the illumination means 111 or 211. For instance, a cable drum system may be used as converting means.

In the first position depicted in Figs. 4a and 4b, the illumination beam produced by the first optical unit is a parallel beam. The optical axis AA, which defines the mean direction of the first illumination beam, has a first position with respect to a support of the illumination system, which is not shown. The illumination system of Figs. 4a to 5b may for instance be used for creating a line of light. In Figs. 4a and 4b, the line of light has the length of the illumination system, because the optical units are such that the parallel illumination beams each have the size of an optical unit. In order to increase the length of the line of light, the optical axes are translated as described above. The illumination system of Figs. 5a and 5b is then obtained. If the size of each illumination beam remained the same during said translation, a plurality of individual light beams would be created, and a dotted line of light would thus be created instead of a continuous line of light. Thanks to the invention, the translation of the optical axes increases the diameter of each illumination beam, which makes it possible to obtain a continuous line of light. As a consequence, an operator may change the length of a line of light obtained by means of such a linear illumination system, only in that a blocking system, for instance, is translated. This makes use of such an illumination system relatively easy.

It should be noted that the illumination systems depicted in the Figs, are for illustrative purpose only. For example, it may be possible that an illumination system in accordance with the invention comprises optical units, which can be rotated and translated with respect to a support, wherein the rotation and/or the translation are converted into a change of vergence of the illumination beam produced by said optical unit.

Any reference sign in the following claims should not be construed as limiting the claim. It will be obvious that the use of the verb "to comprise" and its conjugations does not exclude the presence of any other elements besides those defined in any claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.