CA1292379C - Color wheel assembly for lighting equipment - Google Patents
Color wheel assembly for lighting equipmentInfo
- Publication number
- CA1292379C CA1292379C CA000535786A CA535786A CA1292379C CA 1292379 C CA1292379 C CA 1292379C CA 000535786 A CA000535786 A CA 000535786A CA 535786 A CA535786 A CA 535786A CA 1292379 C CA1292379 C CA 1292379C
- Authority
- CA
- Canada
- Prior art keywords
- filters
- filter
- hub
- color wheel
- light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
- F21S10/00—Lighting devices or systems producing a varying lighting effect
- F21S10/02—Lighting devices or systems producing a varying lighting effect changing colors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
- F21S10/00—Lighting devices or systems producing a varying lighting effect
- F21S10/007—Lighting devices or systems producing a varying lighting effect using rotating transparent or colored disks, e.g. gobo wheels
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
- F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
- F21V9/40—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters with provision for controlling spectral properties, e.g. colour, or intensity
- F21V9/45—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters with provision for controlling spectral properties, e.g. colour, or intensity by adjustment of photoluminescent elements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21W—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO USES OR APPLICATIONS OF LIGHTING DEVICES OR SYSTEMS
- F21W2131/00—Use or application of lighting devices or systems not provided for in codes F21W2102/00-F21W2121/00
- F21W2131/40—Lighting for industrial, commercial, recreational or military use
- F21W2131/406—Lighting for industrial, commercial, recreational or military use for theatres, stages or film studios
Abstract
COLOR WHEEL ASSEMBLY FOR LIGHTING EQUIPMENT
ABSTRACT OF THE DISCLOSURE
A lighting fixture includes a source for producing a beam of light and pair of color wheels.
each of the color wheels has a plurality of dichroic filters mounted on the periphery of the wheel with the filters positioned contiguous to each other. The light beam is directed to a focal point. Each of the color wheels can be rotated to place the peripheral dichroic filters in position to intercept the beam.
One of the color wheels is equipped with long wave pass dichroic filters while the other color wheel is equipped with short wave pass dichroic filters. By aligning various combinations of these filters, a large number of different colors with different saturations can be produced. The cutoff wavelengths for the dichroic filters are selected to be different at the long and short wavelengths of the filter set, such that there is produced a perceived uniform graduation of colors across the spectrum. Each of the dichroic filters mounted on the color wheels is in a shape of a trapezoid and is mounted adjacent other filters, such that there is no blanking of light or leakage of light in the process of changing from one filter to the next.
ABSTRACT OF THE DISCLOSURE
A lighting fixture includes a source for producing a beam of light and pair of color wheels.
each of the color wheels has a plurality of dichroic filters mounted on the periphery of the wheel with the filters positioned contiguous to each other. The light beam is directed to a focal point. Each of the color wheels can be rotated to place the peripheral dichroic filters in position to intercept the beam.
One of the color wheels is equipped with long wave pass dichroic filters while the other color wheel is equipped with short wave pass dichroic filters. By aligning various combinations of these filters, a large number of different colors with different saturations can be produced. The cutoff wavelengths for the dichroic filters are selected to be different at the long and short wavelengths of the filter set, such that there is produced a perceived uniform graduation of colors across the spectrum. Each of the dichroic filters mounted on the color wheels is in a shape of a trapezoid and is mounted adjacent other filters, such that there is no blanking of light or leakage of light in the process of changing from one filter to the next.
Description
B--2.~ ~9 ~ 3~
COLOR WHEEL ASSEMBLY FOR LIG~TING EQUIPMENT
TECHNICAL FIELD OF THE INVENTION
The present invention pertains in general to lighting equipment for producing multiple colors of light and in particular to such equipment which S employs a rotating color wheel which positions different color filters in a beam of light.
3~
BACKGROUND OF THE INvENTION
Lighting effects have become a major element in theatrical and concert performances. As a result of the demand for elaborate lighting in such performances, sophisticated lighting systems have been developed such as disclosed in U.S. Patent No.
4,392,187. This system utilizes a computer to control the position, intensity, size and col~r of the light beams produced by a large number of stage lights.
A particularly important aspect of lighting is that of color. Various color~ must be produced by stage lights for working with a large number of scenes and performances, as well as to provide a specific effect which can be done only by a particular color of light. A number of patents have been filed which disclose various methods and apparatus for providing different colors o light.
U.S. Patent No. 3,816,739 discloses a device which provides colors by varying the intensity of red, blue and green light sources. In U.S. Patent No.
4,319,311 a variety of colors are generated by employing replaceable gelatin color filters in front of the light sources. A f urther method for providing different colors of light i5 disclosed in U.S. Patent r No. 4,071,809, in which a color segmented disk is continuously rotated in front of a strobing light which is timed to flash as a certain color passes in front of the lamp. U.S. Patent No. 4,488,207 discloses a light which has red, yellow and green sources that are angularly disposed with respect to two dichroic filters such that each color can be r either transmitted or reflected from the dichroic ~29~ 9 , filters onto an objective lens. ~ach of the above methods for producing colored light has some drawbacks. In many cases the nu~ber of available colors is very limited. ~he use of gelatin is undesirable as a color filter ~ecause the gela~in has a relatively shor~ life. Cther techniques require either bulky or complex equipment.
I~ previously noted U.S. Patent No. 4,392,t87, there are disclosed two techniques for producing : 10 colored light. One technique provides dichroic filters in the light beam with means for pivoting the dichroic filters for generating light having differen~ colors. The fur~her technique disclosed in - this paten~ for producing colored light is the use of 1g ~ichroic filters mounted in color wheels. Each filter is a round member that is mounted in a wheel, with each filter spaced apart from the adjoining filters. These color wheels are rotated such that the light beam can pass through filters in one or : 20 both of the color wheels. Although this ~echnique has proven to be successful, it still has drawbacks including difficulty of manufacture, expense and blanking of the light beam when the color wheel is : rotated from one filter to another filter.
In view of the above, there exists a need for an inexpensive, reliable color wheel which can be easily mGnufactured, is compact and easy to use, and does not block the light beam when moving from one filter to the next.
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SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a lighting instrument for producing a plurality of colors o~ light from a light source which produces a light beam, comprising: a first rotatable color wheel comprising a first set of dichroic filters mounted about the hub, ~herein each of said filters in said first set can be selectively positioned in said light beam by rotation o~ said first color wheel, said first set of dichroic filters comprising long wave pass filters each of which transmits light having a wavelength greater than a cutoff wavelength of the filter, the cutoff wavelengths of said first set of filters spaced in the visible spectrum at respective intervals, said intervals being greater at longer wavelengths than at shorter wavelengths, a second rotatable color wheel comprising a second set of dichroic filters mounted about the hub, wherein each of said filters in said second set can be selectively positioned in said light beam by rotation of said second color wheel, wherein said second set of filters are positioned such that said light beam can pass sequentially through one filter in said first set and one filter in said second set, and said second set of dichroic filters comprising short wave pass filters each of which transmits light having a wavelength less than a cutoff wavelength of the filter, the cutoff wavelengths of said second set of filters spaced in the visible spectrum at respective intervals, said intervals being greater at shorter . wavelengths than at longer wavelengths.
. According to another aspect of the invention there is provided a color wheel for use in a lighting instrument for producing multiple colors of light, comprising: a hub rotatable about an axis, said hub ha~ing a plurality of filter positions, and a set of planar dichroic filters for transmitting colors when light passes therethrough, each filter joined along one edge thereof to the said hub in a respective position and extending outward from said hub, one said filter position being empty to pass a light beam without imparting color thereto.
~Z~Z3~9 s A still ~urther aspec~ o~ the present invention is the con~iguration of the dichroic ~ilters mounted on the periphery of the hub o~ each color wheel. Each filter is in the shape of a trapezoid, such that a set of ~ilters forms an annular ring on the color wheel.
,, ~
, ~, . . ", E~IEF DESCRIPTION OF TF~E DRAWINGS
For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following Description ta~en in coniunction with the accompanying Drawings in which:
FIGVRE 1 is a perspective ~iew of a lighting : instrument having two rotatable color wheels which can have filters selectively positioned within a beam of light;
FIGURE 2 is an elevation view of a color wheel havin~ a plurality of dichroic filters mounted around the periphery of a hub;
- FIGVRE 3 is a sectional view of the color wheel - shown in FIGURE 2 taken along lines 3-3;
FIGURE 4 is an enlarged section view taken of ~; portion 4 of the color wheel shown in FIGURE 3 for - illustrating the bonding of a dichroic filter to the hub of a color wheel;
FIGURE 5 is a sectional view illustrating an alternative embodiment for joining the dichroic filters to the hub of a color wheel;
FIG~RE 6 is a chart illustrating the cutoff frequencies for the long wave pass and short wave :~ pass dichroic filters implemented in the disclosed ; 25 embodiment of the color wheel of the present inventio~;
FIGURES 7-12 are illustrations of the spectral response characteristics for dichroic filters having complex color characteristics;
FIGURES 13-15 illustrate the resulting colored light spectrum produced by passing the original light beam sequentially throuqh both a long wave'pass and a r short wave pass filter; and .:
-3*9 ( 7 FIGURE 16 is an illustration of the resulting colored light spectrum produced when the original light ~eam is pas3ed sequentially through either a short or long wave pass filter and a complex color filter.
~2~;~3'7~
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention is illustrated in FIGURE 1 as a l~mp assembly 2~ which compri6e~ a lighting instrument. A bulb ~2 produces light which is focused by an elliptic reflector 24 into a light beam 26. At a location 28~ the light beam 26 is concentrated at a focal point by the reflector 24. ~eyond the location 28, the beam 26 expands and is captured by a converging lens 30 which converts the beam 26 into a substantially parallel beam of light.
The lamp assembly 20 further includes a first color wheel 36 and a second color wheel 38. Wheel 36 is mounted on a shaft 40 which is directly driven by a stepper motor 42. The color wheel 38 is mounted on a shaft 44, which is in turn driven by a stepper motor 46.
The color wheel 36 comprises a hub 48 and a set 50 of planar dichroic filters, such as a filter S2, which are mounted on the periphery of the hub 48. An open position 54 is provided on the periphery of the - hub 48 to permit the beam 26 to pass through the color wheel without alteration. The dichroic filters, such as 52, as well as the po~ition 54 are rotatable by the motor 42 into the location 28 at the ; focal point of the beam 26, such that any filter in the set, or the open position, can be placed at this location to alter ~he color of the beam or to pass the beam unaltered.
Color wheel 38 likewise includes a hub 58 having mounted on the periphery thereof a set 60 of planar, dichroic filters, such as a filter 62. Whéel 38 also r includes an open position 64 for permitting the light 37~
g beam 26 to pass through the color wheel 38 without alteration. The color wheel 38 rotates in response to operation of the stepper motor 46 to position any one of the dichroic filters mountea on the hub 58 into the location 28 for altering the color of the beam 26~
Wheel 36 is provided with a reference black stripe 65 and wheel 38 with a similar reference stripe 66. These stripes are used by optical control equipment, not shown, for determining the orientation of the color wheels when the assembly 20 is first activated.
The color wheels 36 and 38 are fabricated in essentially the same manner. For hubs 48 and 58 havin~ a diameter of 5 inches, there is space for 15 filters. The difference between the two color wheels - 36 and 38 is in the transmittance and reflectance characteristics of the dichroic filters mounted on each of ~he wh~el~. The specific characteristics of the various color filters for each color wheel is further described in reference to FIGU~E 6 below.
The color wheel 36 is illustrated in a detailed elevation view shown in FIGURE 2. A section view of - the wheel 36 is illustrated in FIGUR~ 3. A collet 68 is threaded to a central opening in the hub 48.
Collet 68 has a hex head which prevents the collet from passing through the hub 48. Collet 68 has a cylindrical opening 69 which receives ~he shaft 40.
The end of the collet 68 opposite the head is slotted.
The collet 68 is secured to the hub 48 by a nut 70. After the shaft 40 is positioned within the opening 69, a nut 71 is applied to the slotted 12~23~7~
portion of collet 6fl to clamp the collet 6a to the shaft 40.
The hub 48, which is preferably fabricated of aluminum, is provided with a plurality of openin~s, such as 72, for reducing the weight of the color wheel. The combination of the light metal and the multiple o~enings 72 serves ~o reduce the mass, and therefore the inertia, of the color wheel 36. The reduced inertia of the color wheel 36 allows the wheel to be accelerated, moved and stopped faster and with less power than such a wheel having greater weight and inertia~
The hub 4a comprises two laminated aluminum plates 76 and 78. The difference in the diameters of the two round plates 76 and 78 forms a step 80 which is located on the periphery o~ the hub 48. Plate 76 has a plurality of flat peripheral sections, each for receiving one of the filters in the set S0.
All of the filters within the filter set 50, a well as the filter set 60, have the same size and configuration. Each of the filters is in the shape of a trapezoid. Refesring to FIGURE 2, the filter 52 -- has linear sides 52a, 52b, 52c and 52d. m e sides 52b and 52c are parallel. Each of the sides 52c and 52d is aligned with a line which passes through the center of the wheel 36. Thus, each of the filters, such as 52, is in the shape of a trapezoid which is symmetrical about an axis extending from the center of the wheel 36 outward ~hrough the center of the filter.
In a selected embodiment the edges 52a and 52d are 1.05 inches long, the edge 52~ is 0.70' inch long and the edqe 52~ is 1.10 inches long.
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The trapezoidal shape of the filters within the set 50 is particularly advantageous in the manufacture cf the filters. Each filter is cut from a larger sheet of pyrex glass which has been coated with appropriate materials to give the proper color ~ransmission and reflectance. The larger sheet of glass is scribed along lines to give the proper dimensions for the resulting filter, such as 52. m e scribed lines are easily bro~en to form each of the individual filters. Previously, such filters have been manufactured in a circular shape which required cuttinq the glass sheet with a core saw. Filters made in the previous manner result in a substantial waste of the original glass sheet and are more subject to breakage, due to the formation of microfractures around the edges of the circular filter. Such fractures are much less likely to occur ' when the glass sheet is cut with a straight scribe ; line. Thus, the trapezoidal dichroic filters in accordance with the present invention are easier to manufacture, have less waste in the manufacturing process and are less subject to breakage in use.
As a result of the uniform ~rapezoidal shape of the filters within the set 50, the filters as a whole form an annular ring about the hub 48, with the only t opening being the open position 54.
Each of the filters in the set 50, such as filter 52, is mounted on the periphery of the hub 48 and is positioned on the step 80. Each filter in set 50 is bonded to the hub 48 and the filter is directed radially outward from the center of the hub 48. Each of the filters is bonded by an adhesive fi'lm 88. The r step 80 serves primarily as a register to assure the ' ..
1~923~ 9 proper positioning of each of the filters within the set 50. The film 88 is located principally between the filter, ~uch as 52, and the metal plate 78 of the hub 48. This is illustrated in detail in FI~URE 4.
The principal bonding between the filter 52 and the plate 78 is in the region mar~ed by the reference numeral 90. The bonding extends a~ong the lower edge of the f ilter 52.
The adhesive which bonds the dichroic filters to : 10 the hub 48 i5 preferably RTV silicon rubber which is manufactured by both General Electric and DuPont.
The resilient ~ond, film 88, between the glass filter, such as 52, and the aluminum plate 78 has several advantages, in addition to providing a joining between the two members. This adhesive provides a resilient mount for the glass filter which reduces the possibility of cracking the filter when r the filter is subjected to stress. The flexible bond also compensates for the differences in the coefficients of expansion between the aluminum plate 78 and the glass filter 52. Each of the filters in the set 50 is subjected to substantial heating, as is the hub 48. The color wheel 35 must be a~le to function properly, without failure, from room temperature up to approximately 200C. ~he RTV
silicon rubber can withstand this temperature range.
Further referring to the color wheel 36 shown in FIGURE 2, note that the filters are contiguous to 3~ each other along their lateral edges, with the exception of the filters adjacent the open position 54. This configuration of filters provides unique r advantages for the color wheel 36 over previous color 13 ~ z3~
wheels. Conventional color filters are mounted in a wheel wi~h each filter separated by the body of the wheel which acts to block the light from the la~p when the wheel is rotated from one filter to the S next. But when the color wheel 36 is rotated from one filter to the next filter, there is no blocking of the light produced by the lamp assembly 20. There is essentially no change in the intensity of the light, but only a change in its color. This eliminates the distracting blanking that can occur with conventional stage lamps when there is a change from one color filtes to the next. The contiguous positions of the filters also prevents the leakage of light between filters which w~uld occur if the filters were offset from each other on the filter wheel. Should intense white light be permitted to lea~ between the filters, there would be created an unwanted and distracting bright flash in the lighting display.
Referring now to FIGUR~ 5, there is illustrated an alternative embodiment for mounting the dichroic - filters in the set 50 to the hub 48. Filter 52 is butted against the outer edge of the hub 48. In this embodiment the aluminum plate 78 is optional. An adhesive ~ilm 94 is applied between the filter 52 and the plate 76. It is also applied on the immediately ad,oining front and back planar sur$aces of both the ~ilter 52 and the plate 76. Thus, the adhesive film in cross section is in the shape of an ~. Annular rings 96 and 98 are applied on opposite sides of the junction between the filter 52 and the plate 76 to hold the two members in place relative to èach other and provide proper ali~nment for the filter 52.
14 ~Z3~79 The dichroic filters in the sets 50 and 60 are preferably manufactured of pyrex glass having a thickness of approximately .040 inch. Dichroic filters of this type are a~ailable from Technical Products Division of Optical Coating Laboratory, Inc., Santa Rosa, California. The transmittance and reflectance characteristics of each dichroic filter is determined by deposi~ing various layers of material on the pyrex glass in a vacuum chamberO The method of producing such dichroic filters having predetermined ~pectral response characteristics is well known in the art.
The filters within the sets 50 and 60 are arranged about the respective color wheels 36 and 38 in an order from lighter shades to darker shades.
Thus, as the wheels are rotated, there is a smooth transition of colors with gradual steps rather than transmitting spurious colors during a color change.
Referring now to FIGURE 6, there is illustrated a set of spectral characteristics for the filters within set 50 and set 60. In a preferred embodiment of the present invention, the filters within set 50 aee primarily long wave pass ~LWP) fil~ers and the - filters in set 60 are primarily short wave pass (SWP) filters. An LWP filter transmits light havinq a wavelength greater than the filter's cutoff or edge wa~elength. Light having a wavelength less than the cutoff wavelength of the filter is reflected. A SWP
filter transmits light having a wavelength less than the cutoff wavelength of the filter and reflects the light which has a greater wavelength than the cutoff wavelength of the filter.
~Z3~
t ~ 15 The intervals bet~een cutoff wavelengths are shown as ~ values above the long wave pass cutoff wavelengths and below the short wave cutoff wavelengths.
~hen a filter in he set 50 is alig~ed with a filter in the set 60, such that the light beam 26 passes through both filters, there can be selected a desired center wavelength and bandwidth for the light to be transmitted from the lamp assembly 20. This 1~ defines the color and satu ration for the resulting light. By rotating the wheels 36 and 38 to different positions~ a large number of combinations of center wavelength and bandwidth can be selected to achieve a wide range of colors, as well as desired saturation for each color. As an example, assume that the filter 52 in wheel 36 is aligned with the filter 62 in wheel 38. If filter 52 has a long wave pass cutoff of 500 nm and the filter 62 has a short wave pass cutoff of 545 nm, then the resulting light transmitted through the combination of the two filters will have a center wavelength of approximately 522 nm and a bandwidth of 45 nm. Any one of the filters in the sets 50 and 60 can be utilized as a single filter by aligning the open position in the other color wheel at the location ; 28. White light can be transmitted by aligning both of the open positions 54 and 64 to location 28.
A significant feature of the present invention is the spacing of the cutoff frequencies for the dichroic ilters. Prior art dichroic filter sets have spaced the cutoff wavelengths at eve~ increments across the spectrum. It has been discovered that r this does not provide desirable lighting control.
~Z~23'7~3 Specifically, it does not provide uniform steps of perceived color changes across the spectrum. For uniform filter cutoff spacings~ the perceived effect of changes for long wave pass filters is greater at shorter wavelengths than at longer wavelengths. The in~erse is true for short wave pass filters, the perceived effect is much greater at longer wavelengths than at shorter wavelengths. It has been determined that nonuniform spacing of cutoff wavelenqths across the spectrum can provide a more uniform perceived effect. Therefore, in accordance with the present invention, the spacing of the cutoff wavelengths is different at the higher and lower wavelengths for both the long ~ave pass and the short wave pass filters. For the long wave pass filters, the spacing hetween filter cutoffs is less at the shorter wavelen~ths and greater ~t the lon~er wavelengths. For the short wave pass filters, the spacing is greater at the short wavelengths and less at the longer wavelengths. The result of this particular nonuniform spacing of cutoff wavelengths is that the perceived effect is an evenly scaled set - of color values. This gives lighting designers the capability of producing detailed color shadings to create the effects that they desire. Previous color filter systems have not been able to provide the uniformity of color graduations required by lighting designers~
A still further aspect of the present invention is the use of complex color filters (CCF). The characteristic representative ones of these filters are shown in FIGURES 7-12. Each of ~hese charts r represents the normalized response of a CCF across the visible spectrum of 400-700 nm. The color produced by each of these filters is described as follows:
FIGURE 7-- Medium Magenta FIGURE 8-- Light La~ender ~IGURE 9-- Rose Pink FIGURE 10-- Deep Lavender B1ue FIGUR~ 11-- Amber Peach FIGURE 12-- Bright Rose Pink These complex color filters can be mounted on one or both of the color wheels to interact with either the LWP, SWP or other CCF filters.
The results produced by combining various LWP
and SWP filters as well as CCF filters is illustrated in FIGURES 13-16.
FIGURE 13 illustrates the combination of a short wave pass filter and a l~ng wa~e pass filter which aee respectively selected from sets S0 and 60 and simultaneously positioned at the location 28. Th pass band of each filter is shown by single hatching and the resulting pass band is shown by the combined area illustrated by the double hatching.
FIGURE 14 illustrates another combination of a - SWP and a LWP filter with less overlap between the two filters. This results in the production of a color which is more saturated.
F~GURE 15 illustrates a further combination of a SWP and a LWP filter but with the center wavelength of the filter shifted to a longer wavelength portion of the ~pectrum. Again, the double hatched area is the portion of the spectrum which is transmitted from the lamp assembly 20.
r 18 ~ 7~D
FIGUR~ 16 is an illustration of the combination of a CCF with either a SWR or a LWP f ilter. The SWP
and LWP filters are mounted on both of the color wheels 36 and 38. Therefore, the complex color filter can be used with either a short wave pass or a long wave pass filter on the other wheelO ~hen the CCF is combined with a SWP, a portion of energy that would normally be passed by the CCF is blocked. This portion of energy is at the long wave portion of the CCF filter. But if a LWP filter i6 used with the CCF, portions of the 6horter wavelengths can be removed from the CCF to change the shading of the complex color produced by the CCF. In FIGUR~ 16, the reflected portions of the CCF spectrum are shown with single hatching. The capability of subtractinq ~arious high or low wavelengths of the CCF spectrums substantially increases the number and variety of Y colors which can be produced hy the lamp assembly 20 of the present invention.
~0 In summary, the present invention comprises lighting apparatus which provides a very wide variety of light colors with evenly spaced graduations in color. qhe color wheel of the present invention further eliminates the problems of blanking or leaking of light during changes of color filters and has reduced inertia for rapid movement. In a still further aspect, the present invention provides a unique configuration for a dichroic filter, namely a trapezoidal shape.
Although several embodiments of the invention have been illustrated in the accompanying drawings and described in the foregoing Detailed Description, r it will be understood that the invention is not 3~
limited to the embodiments disclosed, but is capable numerous rearrangements, modifications and substitutions without departing from the 8cope of the invention.
COLOR WHEEL ASSEMBLY FOR LIG~TING EQUIPMENT
TECHNICAL FIELD OF THE INVENTION
The present invention pertains in general to lighting equipment for producing multiple colors of light and in particular to such equipment which S employs a rotating color wheel which positions different color filters in a beam of light.
3~
BACKGROUND OF THE INvENTION
Lighting effects have become a major element in theatrical and concert performances. As a result of the demand for elaborate lighting in such performances, sophisticated lighting systems have been developed such as disclosed in U.S. Patent No.
4,392,187. This system utilizes a computer to control the position, intensity, size and col~r of the light beams produced by a large number of stage lights.
A particularly important aspect of lighting is that of color. Various color~ must be produced by stage lights for working with a large number of scenes and performances, as well as to provide a specific effect which can be done only by a particular color of light. A number of patents have been filed which disclose various methods and apparatus for providing different colors o light.
U.S. Patent No. 3,816,739 discloses a device which provides colors by varying the intensity of red, blue and green light sources. In U.S. Patent No.
4,319,311 a variety of colors are generated by employing replaceable gelatin color filters in front of the light sources. A f urther method for providing different colors of light i5 disclosed in U.S. Patent r No. 4,071,809, in which a color segmented disk is continuously rotated in front of a strobing light which is timed to flash as a certain color passes in front of the lamp. U.S. Patent No. 4,488,207 discloses a light which has red, yellow and green sources that are angularly disposed with respect to two dichroic filters such that each color can be r either transmitted or reflected from the dichroic ~29~ 9 , filters onto an objective lens. ~ach of the above methods for producing colored light has some drawbacks. In many cases the nu~ber of available colors is very limited. ~he use of gelatin is undesirable as a color filter ~ecause the gela~in has a relatively shor~ life. Cther techniques require either bulky or complex equipment.
I~ previously noted U.S. Patent No. 4,392,t87, there are disclosed two techniques for producing : 10 colored light. One technique provides dichroic filters in the light beam with means for pivoting the dichroic filters for generating light having differen~ colors. The fur~her technique disclosed in - this paten~ for producing colored light is the use of 1g ~ichroic filters mounted in color wheels. Each filter is a round member that is mounted in a wheel, with each filter spaced apart from the adjoining filters. These color wheels are rotated such that the light beam can pass through filters in one or : 20 both of the color wheels. Although this ~echnique has proven to be successful, it still has drawbacks including difficulty of manufacture, expense and blanking of the light beam when the color wheel is : rotated from one filter to another filter.
In view of the above, there exists a need for an inexpensive, reliable color wheel which can be easily mGnufactured, is compact and easy to use, and does not block the light beam when moving from one filter to the next.
``` ~Z~i~3,~
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a lighting instrument for producing a plurality of colors o~ light from a light source which produces a light beam, comprising: a first rotatable color wheel comprising a first set of dichroic filters mounted about the hub, ~herein each of said filters in said first set can be selectively positioned in said light beam by rotation o~ said first color wheel, said first set of dichroic filters comprising long wave pass filters each of which transmits light having a wavelength greater than a cutoff wavelength of the filter, the cutoff wavelengths of said first set of filters spaced in the visible spectrum at respective intervals, said intervals being greater at longer wavelengths than at shorter wavelengths, a second rotatable color wheel comprising a second set of dichroic filters mounted about the hub, wherein each of said filters in said second set can be selectively positioned in said light beam by rotation of said second color wheel, wherein said second set of filters are positioned such that said light beam can pass sequentially through one filter in said first set and one filter in said second set, and said second set of dichroic filters comprising short wave pass filters each of which transmits light having a wavelength less than a cutoff wavelength of the filter, the cutoff wavelengths of said second set of filters spaced in the visible spectrum at respective intervals, said intervals being greater at shorter . wavelengths than at longer wavelengths.
. According to another aspect of the invention there is provided a color wheel for use in a lighting instrument for producing multiple colors of light, comprising: a hub rotatable about an axis, said hub ha~ing a plurality of filter positions, and a set of planar dichroic filters for transmitting colors when light passes therethrough, each filter joined along one edge thereof to the said hub in a respective position and extending outward from said hub, one said filter position being empty to pass a light beam without imparting color thereto.
~Z~Z3~9 s A still ~urther aspec~ o~ the present invention is the con~iguration of the dichroic ~ilters mounted on the periphery of the hub o~ each color wheel. Each filter is in the shape of a trapezoid, such that a set of ~ilters forms an annular ring on the color wheel.
,, ~
, ~, . . ", E~IEF DESCRIPTION OF TF~E DRAWINGS
For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following Description ta~en in coniunction with the accompanying Drawings in which:
FIGVRE 1 is a perspective ~iew of a lighting : instrument having two rotatable color wheels which can have filters selectively positioned within a beam of light;
FIGURE 2 is an elevation view of a color wheel havin~ a plurality of dichroic filters mounted around the periphery of a hub;
- FIGVRE 3 is a sectional view of the color wheel - shown in FIGURE 2 taken along lines 3-3;
FIGURE 4 is an enlarged section view taken of ~; portion 4 of the color wheel shown in FIGURE 3 for - illustrating the bonding of a dichroic filter to the hub of a color wheel;
FIGURE 5 is a sectional view illustrating an alternative embodiment for joining the dichroic filters to the hub of a color wheel;
FIG~RE 6 is a chart illustrating the cutoff frequencies for the long wave pass and short wave :~ pass dichroic filters implemented in the disclosed ; 25 embodiment of the color wheel of the present inventio~;
FIGURES 7-12 are illustrations of the spectral response characteristics for dichroic filters having complex color characteristics;
FIGURES 13-15 illustrate the resulting colored light spectrum produced by passing the original light beam sequentially throuqh both a long wave'pass and a r short wave pass filter; and .:
-3*9 ( 7 FIGURE 16 is an illustration of the resulting colored light spectrum produced when the original light ~eam is pas3ed sequentially through either a short or long wave pass filter and a complex color filter.
~2~;~3'7~
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention is illustrated in FIGURE 1 as a l~mp assembly 2~ which compri6e~ a lighting instrument. A bulb ~2 produces light which is focused by an elliptic reflector 24 into a light beam 26. At a location 28~ the light beam 26 is concentrated at a focal point by the reflector 24. ~eyond the location 28, the beam 26 expands and is captured by a converging lens 30 which converts the beam 26 into a substantially parallel beam of light.
The lamp assembly 20 further includes a first color wheel 36 and a second color wheel 38. Wheel 36 is mounted on a shaft 40 which is directly driven by a stepper motor 42. The color wheel 38 is mounted on a shaft 44, which is in turn driven by a stepper motor 46.
The color wheel 36 comprises a hub 48 and a set 50 of planar dichroic filters, such as a filter S2, which are mounted on the periphery of the hub 48. An open position 54 is provided on the periphery of the - hub 48 to permit the beam 26 to pass through the color wheel without alteration. The dichroic filters, such as 52, as well as the po~ition 54 are rotatable by the motor 42 into the location 28 at the ; focal point of the beam 26, such that any filter in the set, or the open position, can be placed at this location to alter ~he color of the beam or to pass the beam unaltered.
Color wheel 38 likewise includes a hub 58 having mounted on the periphery thereof a set 60 of planar, dichroic filters, such as a filter 62. Whéel 38 also r includes an open position 64 for permitting the light 37~
g beam 26 to pass through the color wheel 38 without alteration. The color wheel 38 rotates in response to operation of the stepper motor 46 to position any one of the dichroic filters mountea on the hub 58 into the location 28 for altering the color of the beam 26~
Wheel 36 is provided with a reference black stripe 65 and wheel 38 with a similar reference stripe 66. These stripes are used by optical control equipment, not shown, for determining the orientation of the color wheels when the assembly 20 is first activated.
The color wheels 36 and 38 are fabricated in essentially the same manner. For hubs 48 and 58 havin~ a diameter of 5 inches, there is space for 15 filters. The difference between the two color wheels - 36 and 38 is in the transmittance and reflectance characteristics of the dichroic filters mounted on each of ~he wh~el~. The specific characteristics of the various color filters for each color wheel is further described in reference to FIGU~E 6 below.
The color wheel 36 is illustrated in a detailed elevation view shown in FIGURE 2. A section view of - the wheel 36 is illustrated in FIGUR~ 3. A collet 68 is threaded to a central opening in the hub 48.
Collet 68 has a hex head which prevents the collet from passing through the hub 48. Collet 68 has a cylindrical opening 69 which receives ~he shaft 40.
The end of the collet 68 opposite the head is slotted.
The collet 68 is secured to the hub 48 by a nut 70. After the shaft 40 is positioned within the opening 69, a nut 71 is applied to the slotted 12~23~7~
portion of collet 6fl to clamp the collet 6a to the shaft 40.
The hub 48, which is preferably fabricated of aluminum, is provided with a plurality of openin~s, such as 72, for reducing the weight of the color wheel. The combination of the light metal and the multiple o~enings 72 serves ~o reduce the mass, and therefore the inertia, of the color wheel 36. The reduced inertia of the color wheel 36 allows the wheel to be accelerated, moved and stopped faster and with less power than such a wheel having greater weight and inertia~
The hub 4a comprises two laminated aluminum plates 76 and 78. The difference in the diameters of the two round plates 76 and 78 forms a step 80 which is located on the periphery o~ the hub 48. Plate 76 has a plurality of flat peripheral sections, each for receiving one of the filters in the set S0.
All of the filters within the filter set 50, a well as the filter set 60, have the same size and configuration. Each of the filters is in the shape of a trapezoid. Refesring to FIGURE 2, the filter 52 -- has linear sides 52a, 52b, 52c and 52d. m e sides 52b and 52c are parallel. Each of the sides 52c and 52d is aligned with a line which passes through the center of the wheel 36. Thus, each of the filters, such as 52, is in the shape of a trapezoid which is symmetrical about an axis extending from the center of the wheel 36 outward ~hrough the center of the filter.
In a selected embodiment the edges 52a and 52d are 1.05 inches long, the edge 52~ is 0.70' inch long and the edqe 52~ is 1.10 inches long.
~, t ~
;~ 3~7~
The trapezoidal shape of the filters within the set 50 is particularly advantageous in the manufacture cf the filters. Each filter is cut from a larger sheet of pyrex glass which has been coated with appropriate materials to give the proper color ~ransmission and reflectance. The larger sheet of glass is scribed along lines to give the proper dimensions for the resulting filter, such as 52. m e scribed lines are easily bro~en to form each of the individual filters. Previously, such filters have been manufactured in a circular shape which required cuttinq the glass sheet with a core saw. Filters made in the previous manner result in a substantial waste of the original glass sheet and are more subject to breakage, due to the formation of microfractures around the edges of the circular filter. Such fractures are much less likely to occur ' when the glass sheet is cut with a straight scribe ; line. Thus, the trapezoidal dichroic filters in accordance with the present invention are easier to manufacture, have less waste in the manufacturing process and are less subject to breakage in use.
As a result of the uniform ~rapezoidal shape of the filters within the set 50, the filters as a whole form an annular ring about the hub 48, with the only t opening being the open position 54.
Each of the filters in the set 50, such as filter 52, is mounted on the periphery of the hub 48 and is positioned on the step 80. Each filter in set 50 is bonded to the hub 48 and the filter is directed radially outward from the center of the hub 48. Each of the filters is bonded by an adhesive fi'lm 88. The r step 80 serves primarily as a register to assure the ' ..
1~923~ 9 proper positioning of each of the filters within the set 50. The film 88 is located principally between the filter, ~uch as 52, and the metal plate 78 of the hub 48. This is illustrated in detail in FI~URE 4.
The principal bonding between the filter 52 and the plate 78 is in the region mar~ed by the reference numeral 90. The bonding extends a~ong the lower edge of the f ilter 52.
The adhesive which bonds the dichroic filters to : 10 the hub 48 i5 preferably RTV silicon rubber which is manufactured by both General Electric and DuPont.
The resilient ~ond, film 88, between the glass filter, such as 52, and the aluminum plate 78 has several advantages, in addition to providing a joining between the two members. This adhesive provides a resilient mount for the glass filter which reduces the possibility of cracking the filter when r the filter is subjected to stress. The flexible bond also compensates for the differences in the coefficients of expansion between the aluminum plate 78 and the glass filter 52. Each of the filters in the set 50 is subjected to substantial heating, as is the hub 48. The color wheel 35 must be a~le to function properly, without failure, from room temperature up to approximately 200C. ~he RTV
silicon rubber can withstand this temperature range.
Further referring to the color wheel 36 shown in FIGURE 2, note that the filters are contiguous to 3~ each other along their lateral edges, with the exception of the filters adjacent the open position 54. This configuration of filters provides unique r advantages for the color wheel 36 over previous color 13 ~ z3~
wheels. Conventional color filters are mounted in a wheel wi~h each filter separated by the body of the wheel which acts to block the light from the la~p when the wheel is rotated from one filter to the S next. But when the color wheel 36 is rotated from one filter to the next filter, there is no blocking of the light produced by the lamp assembly 20. There is essentially no change in the intensity of the light, but only a change in its color. This eliminates the distracting blanking that can occur with conventional stage lamps when there is a change from one color filtes to the next. The contiguous positions of the filters also prevents the leakage of light between filters which w~uld occur if the filters were offset from each other on the filter wheel. Should intense white light be permitted to lea~ between the filters, there would be created an unwanted and distracting bright flash in the lighting display.
Referring now to FIGUR~ 5, there is illustrated an alternative embodiment for mounting the dichroic - filters in the set 50 to the hub 48. Filter 52 is butted against the outer edge of the hub 48. In this embodiment the aluminum plate 78 is optional. An adhesive ~ilm 94 is applied between the filter 52 and the plate 76. It is also applied on the immediately ad,oining front and back planar sur$aces of both the ~ilter 52 and the plate 76. Thus, the adhesive film in cross section is in the shape of an ~. Annular rings 96 and 98 are applied on opposite sides of the junction between the filter 52 and the plate 76 to hold the two members in place relative to èach other and provide proper ali~nment for the filter 52.
14 ~Z3~79 The dichroic filters in the sets 50 and 60 are preferably manufactured of pyrex glass having a thickness of approximately .040 inch. Dichroic filters of this type are a~ailable from Technical Products Division of Optical Coating Laboratory, Inc., Santa Rosa, California. The transmittance and reflectance characteristics of each dichroic filter is determined by deposi~ing various layers of material on the pyrex glass in a vacuum chamberO The method of producing such dichroic filters having predetermined ~pectral response characteristics is well known in the art.
The filters within the sets 50 and 60 are arranged about the respective color wheels 36 and 38 in an order from lighter shades to darker shades.
Thus, as the wheels are rotated, there is a smooth transition of colors with gradual steps rather than transmitting spurious colors during a color change.
Referring now to FIGURE 6, there is illustrated a set of spectral characteristics for the filters within set 50 and set 60. In a preferred embodiment of the present invention, the filters within set 50 aee primarily long wave pass ~LWP) fil~ers and the - filters in set 60 are primarily short wave pass (SWP) filters. An LWP filter transmits light havinq a wavelength greater than the filter's cutoff or edge wa~elength. Light having a wavelength less than the cutoff wavelength of the filter is reflected. A SWP
filter transmits light having a wavelength less than the cutoff wavelength of the filter and reflects the light which has a greater wavelength than the cutoff wavelength of the filter.
~Z3~
t ~ 15 The intervals bet~een cutoff wavelengths are shown as ~ values above the long wave pass cutoff wavelengths and below the short wave cutoff wavelengths.
~hen a filter in he set 50 is alig~ed with a filter in the set 60, such that the light beam 26 passes through both filters, there can be selected a desired center wavelength and bandwidth for the light to be transmitted from the lamp assembly 20. This 1~ defines the color and satu ration for the resulting light. By rotating the wheels 36 and 38 to different positions~ a large number of combinations of center wavelength and bandwidth can be selected to achieve a wide range of colors, as well as desired saturation for each color. As an example, assume that the filter 52 in wheel 36 is aligned with the filter 62 in wheel 38. If filter 52 has a long wave pass cutoff of 500 nm and the filter 62 has a short wave pass cutoff of 545 nm, then the resulting light transmitted through the combination of the two filters will have a center wavelength of approximately 522 nm and a bandwidth of 45 nm. Any one of the filters in the sets 50 and 60 can be utilized as a single filter by aligning the open position in the other color wheel at the location ; 28. White light can be transmitted by aligning both of the open positions 54 and 64 to location 28.
A significant feature of the present invention is the spacing of the cutoff frequencies for the dichroic ilters. Prior art dichroic filter sets have spaced the cutoff wavelengths at eve~ increments across the spectrum. It has been discovered that r this does not provide desirable lighting control.
~Z~23'7~3 Specifically, it does not provide uniform steps of perceived color changes across the spectrum. For uniform filter cutoff spacings~ the perceived effect of changes for long wave pass filters is greater at shorter wavelengths than at longer wavelengths. The in~erse is true for short wave pass filters, the perceived effect is much greater at longer wavelengths than at shorter wavelengths. It has been determined that nonuniform spacing of cutoff wavelenqths across the spectrum can provide a more uniform perceived effect. Therefore, in accordance with the present invention, the spacing of the cutoff wavelengths is different at the higher and lower wavelengths for both the long ~ave pass and the short wave pass filters. For the long wave pass filters, the spacing hetween filter cutoffs is less at the shorter wavelen~ths and greater ~t the lon~er wavelengths. For the short wave pass filters, the spacing is greater at the short wavelengths and less at the longer wavelengths. The result of this particular nonuniform spacing of cutoff wavelengths is that the perceived effect is an evenly scaled set - of color values. This gives lighting designers the capability of producing detailed color shadings to create the effects that they desire. Previous color filter systems have not been able to provide the uniformity of color graduations required by lighting designers~
A still further aspect of the present invention is the use of complex color filters (CCF). The characteristic representative ones of these filters are shown in FIGURES 7-12. Each of ~hese charts r represents the normalized response of a CCF across the visible spectrum of 400-700 nm. The color produced by each of these filters is described as follows:
FIGURE 7-- Medium Magenta FIGURE 8-- Light La~ender ~IGURE 9-- Rose Pink FIGURE 10-- Deep Lavender B1ue FIGUR~ 11-- Amber Peach FIGURE 12-- Bright Rose Pink These complex color filters can be mounted on one or both of the color wheels to interact with either the LWP, SWP or other CCF filters.
The results produced by combining various LWP
and SWP filters as well as CCF filters is illustrated in FIGURES 13-16.
FIGURE 13 illustrates the combination of a short wave pass filter and a l~ng wa~e pass filter which aee respectively selected from sets S0 and 60 and simultaneously positioned at the location 28. Th pass band of each filter is shown by single hatching and the resulting pass band is shown by the combined area illustrated by the double hatching.
FIGURE 14 illustrates another combination of a - SWP and a LWP filter with less overlap between the two filters. This results in the production of a color which is more saturated.
F~GURE 15 illustrates a further combination of a SWP and a LWP filter but with the center wavelength of the filter shifted to a longer wavelength portion of the ~pectrum. Again, the double hatched area is the portion of the spectrum which is transmitted from the lamp assembly 20.
r 18 ~ 7~D
FIGUR~ 16 is an illustration of the combination of a CCF with either a SWR or a LWP f ilter. The SWP
and LWP filters are mounted on both of the color wheels 36 and 38. Therefore, the complex color filter can be used with either a short wave pass or a long wave pass filter on the other wheelO ~hen the CCF is combined with a SWP, a portion of energy that would normally be passed by the CCF is blocked. This portion of energy is at the long wave portion of the CCF filter. But if a LWP filter i6 used with the CCF, portions of the 6horter wavelengths can be removed from the CCF to change the shading of the complex color produced by the CCF. In FIGUR~ 16, the reflected portions of the CCF spectrum are shown with single hatching. The capability of subtractinq ~arious high or low wavelengths of the CCF spectrums substantially increases the number and variety of Y colors which can be produced hy the lamp assembly 20 of the present invention.
~0 In summary, the present invention comprises lighting apparatus which provides a very wide variety of light colors with evenly spaced graduations in color. qhe color wheel of the present invention further eliminates the problems of blanking or leaking of light during changes of color filters and has reduced inertia for rapid movement. In a still further aspect, the present invention provides a unique configuration for a dichroic filter, namely a trapezoidal shape.
Although several embodiments of the invention have been illustrated in the accompanying drawings and described in the foregoing Detailed Description, r it will be understood that the invention is not 3~
limited to the embodiments disclosed, but is capable numerous rearrangements, modifications and substitutions without departing from the 8cope of the invention.
Claims (20)
1. A lighting instrument for producing a plurality of colors of light from a light source which produces a light beam, comprising:
a first rotatable color wheel comprising a first set of dichroic filters mounted about the hub, wherein each of said filters in said first set can be selectively positioned in said light beam by rotation of said first color wheel, said first set of dichroic filters comprising long wave pass filters each of which transmits light having a wavelength greater than a cutoff wavelength of the filter, the cutoff wavelengths of said first set of filters spaced in the visible spectrum at respective intervals, said intervals being greater at longer wavelengths than at shorter wavelengths, a second rotatable color wheel comprising a second set of dichroic filters mounted about the hub, wherein each of said filters in said second set can be selectively positioned in said light beam by rotation of said second color wheel, wherein said second set of filters are positioned such that said light beam can pass sequentially through one filter in said first set and one filter in said second set, and said second set of dichroic filters comprising short wave pass filters each of which transmits light having a wavelength less than a cutoff wavelength of the filter, the cutoff wavelengths of said second set of filters spaced in the visible spectrum at respective intervals, said intervals being greater at shorter wavelengths than at longer wavelengths.
a first rotatable color wheel comprising a first set of dichroic filters mounted about the hub, wherein each of said filters in said first set can be selectively positioned in said light beam by rotation of said first color wheel, said first set of dichroic filters comprising long wave pass filters each of which transmits light having a wavelength greater than a cutoff wavelength of the filter, the cutoff wavelengths of said first set of filters spaced in the visible spectrum at respective intervals, said intervals being greater at longer wavelengths than at shorter wavelengths, a second rotatable color wheel comprising a second set of dichroic filters mounted about the hub, wherein each of said filters in said second set can be selectively positioned in said light beam by rotation of said second color wheel, wherein said second set of filters are positioned such that said light beam can pass sequentially through one filter in said first set and one filter in said second set, and said second set of dichroic filters comprising short wave pass filters each of which transmits light having a wavelength less than a cutoff wavelength of the filter, the cutoff wavelengths of said second set of filters spaced in the visible spectrum at respective intervals, said intervals being greater at shorter wavelengths than at longer wavelengths.
2. A lighting instrument as recited in Claim 1 wherein each of said filters is located about the periphery of the respective one of said hubs.
3. A lighting instrument as recited in Claim 1 wherein each of a plurality of said filters is positioned contiguous to others of said filters in said set.
4. A lighting instrument as recited in Claim 1 wherein each of said filters has a trapezoidal shape and only one edge of each said filter is connected to the respective hub.
5. A lighting instrument as recited in Claim 1 wherein the filters in each of said sets comprise a substantially closed annular ring about the respective hub.
6. A lighting instrument as recited in Claim 1 wherein the filters in each of said sets are arranged about the respective hubs in an order from lighter color shades to darker color shades.
7. A lighting instrument as recited in Claim 1 wherein each of said filters has a shape with all sides linear.
8. A lighting instrument as recited in Claim 1 wherein each of said hubs comprises first and second plates having different diameters and coaxially joined together to form a step on the periphery of the hub, said step for receiving said filters.
9. A lighting instrument as recited in Claim 1 wherein each of said filters is bonded to the respective hub by a resilient adhesive.
10. A color wheel for use in a lighting instrument for producing multiple colors of light, comprising:
a hub rotatable about an axis, said hub having a plurality of filter positions, and a set of planar dichroic filters for transmitting colors when light passes therethrough, each filter joined along one edge thereof to the said hub in a respective position and extending outward from said hub, one said filter position being empty to pass a light beam without imparting color thereto.
a hub rotatable about an axis, said hub having a plurality of filter positions, and a set of planar dichroic filters for transmitting colors when light passes therethrough, each filter joined along one edge thereof to the said hub in a respective position and extending outward from said hub, one said filter position being empty to pass a light beam without imparting color thereto.
11. A color wheel as recited in Claim 10 wherein each of a plurality of said filters, except two such filters, is positioned between and contiguous to other filters in said set.
12. A color wheel as recited in Claim 10 wherein said filters form a substantially closed annular ring encircling said hub.
13. A color wheel as recited in Claim 10 wherein each of said filters has a shape with all sides linear.
14. A color wheel as recited in Claim 10 wherein each of said filters has a trapezoidal shape.
15. A color wheel as recited in Claim 10 wherein said hub comprises first and second plates having different diameters and coaxially joined together to form a step on the hub, said step for receiving said filters.
16. A color wheel as recited in Claim 10 wherein each of said filters is bonded to said hub by a resilient adhesive.
17. A filter for coloring a light beam comprising a planar glass plate having deposited layers thereon for selectively passing and reflecting spectral portions of said light beam, said plate having a trapezoidal configuration.
18. A filter as recited in Claim 17 wherein the nonparallel sides of said filter are of equal length.
19. A filter as recited in Claim 17 wherein said filter is symmetrical about a center axis.
20. A lighting instrument for producing a plurality of colors of light from a light source which produces a light beam, comprising:
a first rotatable color wheel comprising a first set of dichroic filters mounted about a hub wherein each of said filters in said first set can be selectively positioned in said light beam by rotation of said first color wheel, said first set of dichroic filters comprising at least one complex color filter, a second rotatable color wheel comprising a second set of dichroic filters mounted about a hub wherein each of said filters in said second set can be selectively positioned in said light beam by rotation of said second color wheel, wherein said filters are positioned such that said light beam can pass sequentially through one filter in said first set and one filter in said second set, and said second set of dichroic filters comprising at least one long wave pass filter which transmits light having a wavelength greater than a cutoff wavelength of the filter, and at least one short wave pass filter which transmits light having a wavelength less than a cutoff wavelength of the filter.
a first rotatable color wheel comprising a first set of dichroic filters mounted about a hub wherein each of said filters in said first set can be selectively positioned in said light beam by rotation of said first color wheel, said first set of dichroic filters comprising at least one complex color filter, a second rotatable color wheel comprising a second set of dichroic filters mounted about a hub wherein each of said filters in said second set can be selectively positioned in said light beam by rotation of said second color wheel, wherein said filters are positioned such that said light beam can pass sequentially through one filter in said first set and one filter in said second set, and said second set of dichroic filters comprising at least one long wave pass filter which transmits light having a wavelength greater than a cutoff wavelength of the filter, and at least one short wave pass filter which transmits light having a wavelength less than a cutoff wavelength of the filter.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/863,440 US4800474A (en) | 1986-05-15 | 1986-05-15 | Color wheel assembly for lighting equipment |
| US863,440 | 1986-05-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1292379C true CA1292379C (en) | 1991-11-26 |
Family
ID=25341100
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000535786A Expired - Lifetime CA1292379C (en) | 1986-05-15 | 1987-04-28 | Color wheel assembly for lighting equipment |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4800474A (en) |
| EP (2) | EP0248974B1 (en) |
| JP (4) | JPS62273508A (en) |
| AT (2) | ATE137852T1 (en) |
| AU (1) | AU580213B2 (en) |
| CA (1) | CA1292379C (en) |
| DE (2) | DE3789166T2 (en) |
| ES (1) | ES2050100T3 (en) |
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- 1987-01-24 DE DE3789166T patent/DE3789166T2/en not_active Expired - Fee Related
- 1987-01-24 AT AT87101000T patent/ATE102324T1/en not_active IP Right Cessation
- 1987-01-24 EP EP87101000A patent/EP0248974B1/en not_active Expired - Lifetime
- 1987-01-24 ES ES87101000T patent/ES2050100T3/en not_active Expired - Lifetime
- 1987-01-24 EP EP93250164A patent/EP0565218B1/en not_active Expired - Lifetime
- 1987-01-24 DE DE3751804T patent/DE3751804T2/en not_active Expired - Fee Related
- 1987-03-06 JP JP62050423A patent/JPS62273508A/en active Pending
- 1987-04-28 CA CA000535786A patent/CA1292379C/en not_active Expired - Lifetime
- 1987-05-14 AU AU72934/87A patent/AU580213B2/en not_active Ceased
-
1989
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-
1990
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1991
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Also Published As
| Publication number | Publication date |
|---|---|
| JPH07230711A (en) | 1995-08-29 |
| US4800474A (en) | 1989-01-24 |
| DE3751804T2 (en) | 1996-09-26 |
| EP0565218B1 (en) | 1996-05-08 |
| EP0565218A3 (en) | 1994-01-19 |
| AU7293487A (en) | 1988-01-07 |
| DE3789166T2 (en) | 1994-06-09 |
| AU580213B2 (en) | 1989-01-05 |
| JPH0333413U (en) | 1991-04-02 |
| JP2843696B2 (en) | 1999-01-06 |
| EP0248974A2 (en) | 1987-12-16 |
| JPS62273508A (en) | 1987-11-27 |
| DE3789166D1 (en) | 1994-04-07 |
| EP0565218A2 (en) | 1993-10-13 |
| ATE137852T1 (en) | 1996-05-15 |
| EP0248974A3 (en) | 1989-07-26 |
| ES2050100T3 (en) | 1994-05-16 |
| DE3751804D1 (en) | 1996-06-13 |
| ATE102324T1 (en) | 1994-03-15 |
| JPH0472321B2 (en) | 1992-11-18 |
| JPH03122903A (en) | 1991-05-24 |
| EP0248974B1 (en) | 1994-03-02 |
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