GB2316477A - Lighting system with beam shape control - Google Patents

Abstract

A light for stage or theatre use includes a lens which can be moved into the main light beam L to change the beam shape, eg circular to elliptical. A rotary lens wheel 88 is disclosed having four openings of which 188 a and 188 b include lens elements 288 a , 288 b formed with a plurality of elongate parallel lenticules 388 a extending either radially or transversely of the wheel axis. A diffuser 288 c and a blank opening are also provided. The lamp may include a second similar wheel (claimed in the parent), conventional colour wheels, filters for heat, IR and UV and motors with control circuits for pan and tilt movements in a yoke mounting.

Description

LIGHTING SYSTEM This invention relates to a lighting system, generally to stage and theatre lighting fixtures and more particularly to a colour wash luminaire which provides variable intensity, variable colour, variable positioning and variable beam shapes and angles in a single compact fixture.

Wash lights, as they are generally known, are used to provide uniform illumination and colouration to a theatrical set. Lights used in a studio or for photographic purposes often project a round cross-sectional pattern of light such as that seen by the ordinary flashlight. Simple devices utilise a reflector and a lamp or utilise sealed beam lamps, such as automotive head light type lamps. These sealed lamps consist of a reflector, a lamp and a type of diffuser or lens to soften the projected spot, and sometimes to focus the projected spot from either a narrow spot or a wide flood. More complicated arrangements involve ellipsoidal reflectors or condensing systems which focus light through an aperture which is imaged by projector lenses.

These types of systems commonly produce a more uniform beam of light than that of the sealed beam type. Other types of lights used include fresnel projectors, which utilise a fresnel projecting lens. The fresnel projecting lens is known to provide a beam of light that is homogeneous with a gradual roll-off of light output toward the edges. Many of the things illuminated on a stage or studio do not always require a round beam of light since many stages or studio sets can often be more wide than they are tall.

Illuminated subject areas often require the use of a framing projector or devices known as barn doors which can be utilised to change cross-sectional pattern or the shape of the beam by shadowing the light projected from the device as a means to change the shape of the beam.

According to one aspect of the present invention there is provided a light fixture having a lens apparatus for changing a shape projected by a beam of light, comprising means for projecting a beam of light, the beam projecting a first beam shape having a first cross-sectional geometry; a lens device supported in the fixture and movable into a position to interrupt the beam of light for altering the first projected beam shape from the first cross-sectional geometry to a second projected beam shape having a second cross-sectional geometry different from the first geometry, the lens device including at least one lens element and a mechanism for moving the lens device.

According to a second aspect of the present invention there is provided a moving light fixture comprising a yoke, means for movably suspending the yoke from a support, a housing movably connected to the yoke, the housing having a first portion including a light source and means for removing heat generated from the light source, and a second portion including a plurality of movable colour filters and a lens device, the light source being operable to project a beam of light having a first beam shape of a first crosssectional geometry, along a path through the colour filters and the lens device; the lens device being supported in the fixture and being movable by a mechanism into a position to interrupt the beam of light for altering the first projected beam shape from the first cross-sectional geometry to a second projected beam shape having a second cross-sectional geometry different from the first geometry, the lens device including at least one lens element.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Fig. 1 is a frontal view, with partial cutaway portions, illustrating an embodiment of a luminaire, Fig. 2 is a perspective view, with partial cutaway portions, of the luminaire, Fig. 3 is a cross-sectional view of a housing, Fig. 4 is a perspective view, with partial cutaway portions, of the housing, Fig. 5 is another perspective view, with partial cutaway portions, of the housing, Fig. 6 is a plan view of a colour filter, Fig. 7A is a planar view illustrating a rotatable lenticular lens device, Fig. 7B is a planar view illustrating another rotatable lenticular lens device, Fig. 8 is a diagrammatic view illustrating a power board, Fig. 9 is a diagrammatic view illustrating a logic board, Fig. 10 is a side view illustrating another embodiment of the luminaire, and Fig. 11 is a perspective view illustrating an embodiment of a hot plate and ultra violet filter.

This invention is intended to cover overlapping rotating lens devices each including lenticular lens elements movable into a position to interrupt a beam of light for selecting beam shape by altering a circular beam pattern to ellipsoidal beam patterns and for moving the ellipsoidal beam patterns to a desired orientation.

Referring to the drawings, Figs. 1 and 2 illustrate a wash luminaire generally designated 10. The luminaire 10 comprises a housing 12 connected to a yoke 14 which may be suspended from a supporting truss (not shown) by means of a clamp (also not shown) attached to the yoke 14 at a connector 16.

The yoke 14 comprises a suitable metal frame 18 including a metal bracket 20 to reinforce the yoke 14. The connector 16 is bearing mounted and connected by means of a shaft 22 to a gear 24 positioned adjacent the bracket 20. The gear 24 includes a notch (not shown) which operates with an adjacent position sensor (not shown) for pan position control. A motor 26, supported by the frame 18, drives a belt 28 to rotate the gear 24 for the purpose of providing a 360 degree rotation about a centroidal axis P of the shaft 22. This provides the pan capability to the luminaire 10. A suitable idler arrangement 30 is provided to the engage belt 28.

Another motor 31, also supported by the frame 18, drives a belt 32 to rotate a gear 34 for the purpose of providing at least a 270 degree rotation about the centroidal axis T of a shaft 36. Similar to the gear 24, the gear 34 includes a notch 34a which operates with an adjacent position sensor 34b for tilt position control. This provides the tilt capability to the luminaire 10. Another suitable idler arrangement 38 is provided to the engage belt 32. A travel stop 37 is connected to the tilt mechanism to limit movement of the luminaire 10 to a desired tilt angle.

A manual off-on switch or breaker 52 is also mounted externally on the yoke 14. A cooling fan 48 mounted in a housing 50 is operable to draw cooling air into the yoke 14 through a plurality of vents 54, across the internal components of the yoke 14 and outwardly through a similar plurality of vents 56. A cover 59, formed of a rigid synthetic material, which includes the vents 54 and 56, encloses the yoke 14 and the above described components.

In Figs. 3, 4 and 5, the housing 12 is illustrated and generally comprises an aluminium casting 57 and a bezel 58, formed of a suitable rigid synthetic material. The casting 57 includes a base 60, at a first end, from which a first plurality of contoured external cooling fins 62 extend. A stepped annular relief 66 is provided within the casting 57 and includes an annular portion 64 and a truncated elliptical portion 69. The annular portion 64 also includes cooling vents 65. A second plurality of internal cooling fins 63 are disposed about an inner annular periphery of the annular portion 64. The first and second fins 62, 63, respectively, are aligned.

An aluminium end cap 68 is mounted on a second end of the casting 57. A lamp base 70 and lamp 72 are mounted on the end cap 68. The lamp 72 extends into open annular relief 66. An elliptical reflector 74 is also mounted in elliptical portion 69 so as suitably to surround the lamp 72. The lamp 72 is powered by AC power in a conventional manner.

An aluminium heat blocking wall, or hot plate 76, is mounted on the first end of the casting 57, and is spaced from a motor mounting plate 78 by spacer elements 80. A plurality of motors 82 are mounted on the motor mounting plate 78 and rotating shafts 84, extending from the motors 82, are operable to be belt driven to rotate a plurality of staggered colour filters 86, a pair of overlapping, staggered lenses 87, 88 and a conventional colour wheel 89.

Tabs, such as tab 86a, on the colour filter 86 are provided on these shaft mounted, rotating lenses, filters, etc., to operate with a plurality of respective adjacent position sensors 257 mounted on a pair of motor/driver sensor boards 94 mounted between the plates 76, 78 for the purpose of sensing the positions of each of the shaft mounted rotating devices including the colour filters 86, etc.

A light beam L, Fig. 3, is condensed to a diameter of about 1.25 inches (31.75 mm) in diameter where it exits the casting 57 at an opening 76a in the hot plate 76. The beam then passes through the series of wheels, colour filters, lens, etc. In the embodiment of Fig. 3, the bezel 58 houses a series of six wheels: colour wheel 89, dichroic coated colour filter (yellow) 86y, dichroic coated colour filter (cyan) 86c, dichroic coated colour filter (magenta) 86m, and lenses 87 and 88. Three of these wheels are mounted on one of the shafts 84 and another three are mounted on a corresponding shaft 84. The two sets of three wheels are interleaved, i.e. partially overlapped, in known fashion, to optimise the number of surfaces exposed to the beam L. The positions of the three wheels on one shaft 84 are sensed by their respective sensors 257 on one of the boards 94 and the positions of the other three wheels on the other shaft 84 are similarly sensed by their respective sensors 257.

The colour filters 86y, 86c and 86m, Fig. 6 comprise a disc-shaped borosilicate glass substrate 301 having a planar surface 302 which includes a photolithographically etched film 303 deposited thereon. Film 303 forms a Gausian pattern arcuate band 304 extending around a substantial portion of the planar surface 302. The band 304 has an inner edge 305 and an outer edge 306 and the density of film 303 is greater in an area designated g+ along a radius r between the inner edge 305 and outer edge 306 and less in an area designated g- along radius r at the inner edge 305 and less in a corresponding area g- along radius r at the outer edge 306. A portion of substrate 301 is cut away to form a notch 307 which interrupts the arcuate band 304. A portion p of planar surface 302 adjacent the notch 307 is coated with a solid film 303a having no pattern as on the etched film 303 in the band 304.

The colour filters 86y, 86c and 86m are used in combination with the lamp 72 to produce desired colour effects. The beam L, produced by the lamp 72, is circular and has a typical power gradient, which is not uniform across the beam. A ratio of power from the centre of the beam to the beam edge is often on the order of 50%. Known variable density filters which do not address the power gradient of the beam produce results which are non-uniform and leave an apparent white spot in the centre of the beam while darkening the beam edge which makes the colouration objectionable.

Advantageously, the Gausian patterning of the colour filters is coincident with the inverse of the power gradient of the beam L. That is, the colour filter gradient is greatest toward the centre of the band 304 where it crosses the maximum power point of the beam L. In this manner, the maximum power of the beam L is coincident with the maximum filtering effect of filters 86y, 86c and 86m.

Saturation of the Gausian colour pattern increases proportionally as the filter is rotated in a direction represented by directional arrow D, Fig. 6, culminating in 100% saturation at about 300 degrees of angular travel where portion p of the planar surface 302 is coated with the solid film 303a.

If it is desired, a bracket 90 is mounted on the hot plate 76 to position a heat filter 92 to reflect IR radiation R back to the cooling fins 63, 62 to be dissipated from the housing 12. The heat filter 92 comprises the bracket 90, Figs. 3 and 4, which is generally of an A-frame construction and includes a first filter 98a mounted at about a ninety degree angle relative to a second filter 98b. The filter 92 is used to reflect damaging infrared radiation R away from the previously mentioned heat sensitive optical components mounted on the shafts 84.

Thus, these filters are at an angle to the light beam L passing therethrough. The result is a reflection of IR radiation outwardly toward the fins, as is best shown in Fig. 3. The first and second filters 98a, 98b, respectively, are preferably formed of a suitable 1.75 mm thick substrate of borosilicate glass material and has a thin film dichroic coating on both sides. The coating on one side facing lamp 72 will provide infrared reflectance of from about 730 nm to about 1,050 nm. The coating in the opposite side will provide reflectance of from about 1,050 nm to about 1,700 nm.

The heat filter 92 can be omitted. However, preferably a filter for blocking ultra violet rays from reaching the colour wheels and their drive systems may be utilised.

Such a filter 592, Fig. 11, may take the form of a borosilicate glass material positioned between the lamp and the colour wheels. For example, the filter 592 may be suitably mounted on the hot plate 76 in place of the heat filter 92 in position to filter the light beam L before it passes through the opening 76a in the hot plate 76.

A lenticular lens device 88, Fig. 7A, is rotatably mounted adjacent one side of the motor mounting plate 78. The lens device 88 is mounted on one of the shafts 84 which is rotatably driven by one of the motors 82 suitably attached on another side of the motor mounting plate 78. The lens device 88 comprises a disc shape and is formed of an aluminium or other suitable metal retainer 188 having a plurality of openings 188a, 188b, 188c, 188d formed therein. An aperture 188e in the geometric centre is for receiving the shaft 84 whereby the lens device 88 is rotatable. One of the openings 188a includes a lenticular lens element 288a formed of a suitable high temperature glass having a plurality of substantially parallel radially extending grooves or lenticules 388a formed therein.

Another of the openings 188b includes substantially the same lenticular lens element 288b but having the grooves or lenticules 388b orientated at 90 degrees relative to the lenticules 388a. The lenticular lens elements 288a and 288b will change the geometric shape from a circular to an elongate ellipsoidal shape. Still another of the openings 188c includes either a suitable well known frost material 288c, Fig. 7A, which will diffuse and soften the beam L and spread out the beam angle but will not affect the geometric shape of the beam. The last of the openings 188d remains open and contains no lens element so that the light beam passing therethrough retains its normal light pattern having a circular cross-sectional geometry. The lens elements 288a, 288b, 288c or 488c may be fixedly secured to the retainer 188 by a suitable high temperature silicone based adhesive or may be removably secured by some suitable attachment device.

Another lenticular lens device 87, Fig. 7B, is rotatably mounted similar to the device 88 but staggered to overlap the device 88. The lens device 87 is similar in construction to the device 88 except that a homogeneous lens element 488c is provided in place of the frost material 288c of the device 88. As it is known, the homogeneous lens element 488c includes an array of adjacent convex surfaces which function to change the magnification and increase the beam angle but will not affect the geometric shape of the light beam L. As a result, the lens device 87 includes a lenticular lens element 288a' having a plurality of substantially parallel, radially extending grooves or lenticules 388a' formed therein and the lenticular lens element 288b' having grooves or lenticules 388b' orientated at 90 degrees relative to the lenticules 388a'. The homogeneous lens element 488c is provided instead of frost material 288c, and 188d' remains open.

When the device 88 is mounted in the fixture 10 for rotation on the shaft 84 engaged in the aperture 188e, the fixed beam of light L passes through the lens device 88 as the device 88 is rotated. When the opening 188d is in the path of the beam L, there is no affect on the beam since there is no lens in the opening 188d. When the device 88 is rotated to a position where the frosted lens 288c interrupts the beam L, the beam angle is affected but the geometric shape of the beam L is unchanged. However, when the lenticular lens elements 288a and/or 288b interrupt the beam L, the normally projected circular geometric shape of the beam L is changed to an oblong or ellipsoidal shape 0 as illustrated in phantom in Fig. 7A. Furthermore, as the lens device 88 is rotated through the fixed beam L, the oblong shape of the beam 0 changes in orientation.

For purposes of illustration only, several radii are shown in Fig. 7A and extend outwardly through six different positions where the rotating lens device interrupts the fixed beam L. In a first position the orientation of altered beam Ol on radius R1 is aligned with the direction of the lenticules 388a as they extend across beam L1 which remains fixed. As viewed in Fig. 7A, the oblong projected beam O1 is slightly canted to the right with reference to radius R1. In a second position, the orientation of altered beam 02 on radius R2 is aligned with the direction of the lenticules 388a as they extend across fixed beam L2 which is actually in the same fixed position as the beam designated L or L1. As viewed in Fig. 7A, the longitudinal axis of the projected beam 02 is vertically aligned with reference to radius R2 and as the lens device 88 is further rotated, the oblong projected beam 03, 04, 05 and 06 constantly changes orientation in the direction of rotation with reference to its respective radii R3, R4, R5 and R6 due to the changing orientation of lenticules 388a and 388b extending across the fixed light beam.

With the foregoing orientation description in mind, it can be appreciated that the overlapping lens devices 87, 88 provide a wide variety of beam shapes including combinations of beam shapes heretofore not available. The combinations include circular and ellipsoidal beam shapes with or without frost, with or without increased beam angle, or with overlapping ellipsoidal beam shapes, for example where lens element 288a overlaps lens element 288b' wherein the ellipsoidal beam shape provided by one lenticular lens element, i.e. 288a, can extend in a longitudinal direction which is angularly disposed relative to the longitudinal direction of the ellipsoidal beam shape provided by another lenticular lens element, i.e. 288b', of an overlapping lens device. This unique combination provides enhanced lighting effects not previously available.

Also included in the yoke 14 is a power supply board 146, illustrated in Fig. 8, mounted behind a portion 46 of the metal frame 18. The power supply board 146 is the motor and logic power supply for movement of the luminaire 10.

The power supplied to the board 146 may be 100 to 240 volts AC (50/60Hz). A voltage selection rectification 148 changes AC to DC voltage and operates to double the voltage if less than 150 volts AC. Output is stored in capacitors 150, 151 and then a half bridge 152 switches the DC back to AC voltage at 40kHz. The 40 kHz goes into a transformer 154 which steps the voltage down and isolates the live voltage from the low voltage output circuit. The AC voltage is rectified back to DC voltage and filtered via an inductor-capacitor arrangement at 156. A voltage mode, pulse width modulator controller 158 is responsible for the feedback of the output voltage and controls the half bridge 152 to produce a constant output voltage. Also, a voltage sensor for doubler circuit control is provided at 160.

A logic board 246, illustrated in Fig. 9, is mounted in the yoke 14 behind a portion 40 of the metal frame 18. The logic board is operably connected to a controller and controls the above-mentioned pan and tilt, and also controls the colour wheels, etc. and other operable components of the luminaire 10. Power from the power board 146 is fed to the logic board 26 at from about 9 volts DC to about 40 volts DC through a voltage regulator circuit 248. The power is then communicated to a commercially available embedded microprocessor 250. The power is also communicated to a memory block 252 which comprises 3 different types of memory including Static RAM, Flash ROM and EPROM. The memory 252 is utilised by the microprocessor 250 to perform read/write operations on the code and data stored in the 250 memory which signals pan and tilt commands to the luminaire 10. A serial transceiver 254 provides RS 485 compatible signals to industry standard USITT DMX512 controllers and exchanges (receives and transmits) information with microprocessor 250. A slave serial module 256 receives information from the microprocessor 250 and serialises data received and sends it out over five wires to the slave modules including motor driver/sensor boards 94 which include infrared photo interrupter sensors 257, Fig. 3, which respond to tabs and/or notches on component parts of the luminaire 10 such as notch 34a formed in the gear 34, Fig. 2 or tab 86a on the colour filter 86, Fig. 3, which tells the microprocessor 250 the initial (zero or homing) position of the motors 26, 82, respectively. The serial module 256 retrieves the position information from sensors 257 and sends it to the microprocessor 250 which determines whether to continue to move the filter or gear or to look for the tab/notch.

Another arrangement is illustrated in Fig. 10 and includes a fixture housing 510, a yoke 514 and an electronics housing 516. In this arrangement, the power board 146 and logic board 246, Figs. 8 and 9, are positioned in an electronics housing 516. Also, in the housing 516 are the previously described motor 26, bolt 28 and gear 24 arrangements, see Fig. 1, for driving the 360 degree pan position control which rotates the housing 510 about centroidal axis P of a shaft 522 which interconnects a yoke 514 and electronics housing 516. No fan such as the fan 48, described previously as being positioned in the yoke 14, and co-operative vents 54, 56, are needed, with removal of the electronics including the logic board 246 and power board 146 from the yoke. The previously described tilt mechanism, see Fig. 1, including the motor 31, belt 32 and gear 34, would however remain in the yoke to provide the 270 degree rotation. The housing 510 may also include contoured, radially directed cooling fins 562 formed as part of a aluminium casting 557.

A stationary lens 96 is mounted in the bezel 58 (Fig. 1).

The lens 96 is a common light diffusing lens similar to a lens used in an automotive headlight. Such lenses are commercially available. The above described combination of overlapping, rotating lenses 87, 88 and stationary lens 96 provide a beam angle which is preferably from about 10 degrees to about 60 degrees. This can be varied by rotation of the lenses 87, 88 and enhanced by interchanging a selected diffusing lens 96.

This application is a divisional application divided from United Kingdom Patent Publication No. GB-A-2307036 (application No. 9615544.5) which is incorporated herein by reference.

Claims (15)

CLAIMS:

1. A light fixture having a lens apparatus for changing a shape projected by a beam of light, comprising means for projecting a beam of light, the beam projecting a first beam shape having a first cross-sectional geometry; a lens device supported in the fixture and movable into a position to interrupt the beam of light for altering the first projected beam shape from the first cross-sectional geometry to a second projected beam shape having a second cross-sectional geometry different from the first geometry, the lens device including at least one lens element and a mechanism for moving the lens device.

2. A moving light fixture comprising a yoke, means for movably suspending the yoke from a support, a housing movably connected to the yoke, the housing having a first portion including a light source and means for removing heat generated from the light source, and a second portion including a plurality of movable colour filters and a lens device, the light source being operable to project a beam of light having a first beam shape of a first crosssectional geometry, along a path through the colour filters and the lens device; the lens device being supported in the fixture and being movable by a mechanism into a position to interrupt the beam of light for altering the first projected beam shape from the first cross-sectional geometry to a second projected beam shape having a second cross-sectional geometry different from the first geometry, the lens device including at least one lens element.

3. A fixture according to claim 1 or 2, wherein the lens device is rotatably mounted in the fixture.

4. A fixture according to claim 1, 2 or 3, wherein the lens device is a disc rotatably mounted in the fixture.

5. A fixture according to claim 4, wherein the disc includes a plurality of lens elements mounted for automated sequential positioning in the beam of light.

6. A fixture according to any one of the preceding claims, wherein in use the first projected beam shape is of a circular cross-section, the second projected beam shape is of an ellipsoidal cross-section having a longitudinal axis extending in a first direction.

7. A fixture according to claim 4 or 5, wherein the disc includes a frost lens element and at least one lenticular lens element.

8. A fixture according to claim 4 or 5, wherein the disc includes at least one lenticular lens element having lenticules extending radially outwardly from the geometric centre of the first disc.

9. A fixture according to any preceding claim, in which said mechanism is operative to move the lens device so as to change the angular orientation of the lens device through which the beam passes.

10. A fixture according to any preceding claim in which said mechanism is operative to rotate the lens device so as to change the portion or element of the lens device through which the light beam passes.

11. A fixture according to any preceding claim, in which the axis of incident light beam and the axis of rotation of the lens device are non-concentric.

12. A fixture according to claim 11, in which the axis of rotation of the lens device is parallel but not colinear to the centre axis of the light beam.

13. A fixture according to any preceding claim, in which the axis of rotation of the lens device is outside the cross sectional area of the light beam.

14. A fixture according to any preceding claim, in which said at least one lens element is a lenticular lens element having a plurality of lenticules orientated in a first direction.

15. A lighting fixture, substantially as hereinbefore described with reference to any one of the embodiments shown in the accompanying drawings.