US2651743A - Lighting control system - Google Patents

Description

Sept. 8,` 1953 R. G. WILLIAMS LIGHTING CONTROL SYSTEM Filed Oct. 2, 1950 4 Sheets-Sheet l ATTORNEY.

Sept. 8, 1953 R. G. WILLIAMS 2,551,743

LIGHTING CONTROL SYSTEM Filed oct. 2, 195o L 4 sheets-sheet 2 IOO . INVENTOR. ROLLO GILLESPIE WILLIAMS ATTORNY.

Sept. 8, 1953 R. G. WILLIAMS LIGHTING CONTROL SYSTEM.

4 Sheets-Sheet 3 Filed 001;. 2, 1950 mOFOE OP w .G n...

INVENTOR.

ROLLO GLLESPIE WILLIAMS ATTORNEY.

Sept. s, 1953 Filed Oct. 2. 1950 4 Sheets-Sheet 4 E S U E R T R A H C m E lm 5 m N w P ww m RR .mv 5 T ww S0. 7 E oL uw mu. mm www Tm T .um w s 5 mw LQ 4 R o no E A f 3 P CN 2 Eo sm O5 LR M A 5 mw M nlv 3 I E L w H A PE m DB T PIN K LAVENDER FIG. 7a

INVENTOR. ROLLO GILLESPIE WILLIAMS ATTORNEY.

Patented Sept. 8, 1953 LIGHTING CONTROL SYSV'IEM Rollo Gillespie Williams, Great Neck, N; Y., as-` signor,

by mesne assignments, to Duro-,Test

Corporatin,4 North.E Bergen, N. J., a corporatipnjf New York Application October Z, 1950, Serial No. IS7-,958 22 Claims..` (Cl. 3.1;5ff191) rIhis invention relates to lighting coritrol systems and particularly to. ar novel method and means for controlling the selection of hues ot colors in a color lighting system and also the light values of the. selected hues and combi-ning the hues thus selected whereby illumination having a wide range, ofA resultant hues of,` colorl will beproduced.

In the systems ofy color lighting using a plurality ofl sources of color, such as those systems largely employed heretofore in theatres, motlon picture. houses, shop windows, ball-rooms, and. other places where color lightingis desired either for dramatic eilect or for decorative or display purposes, it has been found necessary to employ in the controlV apparatus more than one brightness control for the plurality of sources of color. This requirement obviously not onlyA greatlyincreases the` cost ofthe control apparatus but also.

necessitates greater space forl containing` it. One

of the objects ofV the present invention. is, to minimize the cost and the space requirements of a color lighting systemA employing-- a plurality of sources of color, that effect being attained by novel means in which the voltage regulation of a plurality of-sources of color is effected by means of a single brightness control.

In the production of pastel hues of color in. a color lighting system by combining white light with colored light, it is of course necessary toA maintain the intensity ofthe white illumination at a low value with respect tothe light values of the colored illumination in order to prevent the. overpowering of the` colored light by 'white light which would result in the production o-i owhite illumination instead of pastel hues` In the. present invention, in which electrical. sources of white light and colored light are employed, the control of' the intensity of the White light is,v et,` footed a novel and unusual arrangement of the control circuit by which one of the sources of. coloredv light is connected in series with the source of white light s c as to. reduce the, voltage applied to the source of white light, the source of, colored light thus connected in series with the white light being one which during the period of activation of the` other sources of light would otherwise remain inactivated. Iny a lighting system employing red, green, blue,` and white, in which one of the. sources of color isv connected in series with the source oi white to reduce its in tensity, as mentioned above, the pastelling effect` plodued. by White light. 0i reduced intcnsity'is enhanced by the Halli Produced. bv the color sat1-Ge that. in .Series with the white Salime since the hue` cf that color source is always the complementar-y hue of that produced by the. other,

transformer in which some of the turns of the.

windingI at the hist-1 voltage' end thereQf; Were replaced by a conductive plate. onto which the movable contact member oi the transformer would ride when it reached that end of the coil, such arrangement being essential to avoid the burning out of the transformer by the short-circuiting` oi one ora fewv turns of the winding at the high-voltage end during the switching operations of the control circuit. One of the advantages of the present invention, which will be fully described hereinafter, resides in the fact that the switching means employed entirely removes the possibility of short-circuiting any of the turns of the Winding Of the transformer during the cperation of the control apparatus .and therefore permits the. employment of standard types of auto-transtorrners.

The invention is further characterized by the inclusion of a chromaticv scale showing the hues of colorthat are. attain-able by. this invention, the scale. having associated with it a pointer the Inoyements of which result from those of a controlK knob whereby the apparatus may be set to produce illumination of any desired color.

Furthermore, each control unit is larranged not only for the manual adjustment of the apparatus contained in said unit whereby any hue of color upon the associated chromatic scale may be produced at will by the group of lamps controlled by said apparatus but the unit is also designed to be motor-operated whereby the entire range of h ues of colors of said scale may be repetitively produced. Furthermore, said apparatus is arranged to be locked in either the manually-operated position or the motor-operated position, as desired. Obviously, a plurality of such units may bev grouped in a suitable framework so that all maybe operated by the same driving means. Furthermore, since the control units may be readily changed from the manually-operated Dosition to the'motor-operated position, and vice Versa, and locked in either of said positions, certain units in such a group of units may be set for motor-.operation and others set for manual-operation, thereby producing an illumination eiect in which the. colors repetitively produced by the light sources controlled by the motor-operated units will be contrasted with the hues of color of the light sources controlled by the manually-operated units, and indicated by the particular setting thereof. For example, one of the units in a group may control one set of side lights in a window lighting system, a second unit may control another set of side lights, and a third unit may control the set of lights at the top of the window, and the units of the group may be adjusted so that the illumination from the side lights will continuously vary while that from the top lights will remain fixed thereby producing the desired color effect. When all units are connected so as to be operated continuously, they may be set to begin the production of color at different points upon a chromatic scale, such as that described hereinafter, and after being thus set, the switching mechanism of the several units will maintain throughout the entire sequence of hues of color the same relationship between the hues produced by the several units that existed at the initial setting of the units, thereby producing unusual and striking color effects.

Other objects of this invention will be apparent from the following description when read in connection with the attached drawing in which:

Fig. 1 is a circuit diagram representing one form of the invention;

Fig. 2 is a chart showing the time of operation of the cams shown in Fig. l throughout the one complete color cycle of 360;

Fig. 3 shows the voltage curve of the single dimmer employed in this invention throughout a complete color cycle, and also shows the curve of intensity of white light in lumens corresponding to the voltage variation;

Fig. 4 is a perspective view of one form of the driving and timing apparatus employed in the circuit shown in Fig. 1; and Fig. 4a is a detail of the apparatus shown on Fig. 4;

Fig.I 5 is a circuit diagram of a modification of the circuit in which the present invention is employed;

Figs. 6, 6a, and 6b show an arrangement for coupling together a plurality of control units and operating them from the driving means connected to one of said units.

Figs. '7 and 'lla are modifications of a portion of the circuit of Fig. 1, Fig. 7 showing means by which the normally inactive source of color in a three color lighting system may be beneficially employed by connecting said source to the dimmer in series with a resistance to control the intensity of light of said source; and Fig. 7a shows means by which the normally inactive source of color in a four color lighting system may be employed either in combination with two of said colors as in Fig. 7 or with three of said colors in the manner shown in Fig. l.

Figs. 8 and 8a are modifications of a portion of the circuit in Fig. 5 showing two other ways in which the intensity of the white light in said circuit may be controlled; and

Fig. 9 is Ia color chart for use in a lighting system employing white, red, green, and blue sources of light showing the range of hues of color resulting from the sequence of adjustments of the apparatus in which the present invention is embodied.

Throughout the following description of this invention, it has been assumed, for the purpose of illustration, that each source of white light is an incandescent lamp and that colored light is obtained by passing white light through color filters in the manner described in my book entitled The Technique of Stage Lighting published in 1947 by Sir Isaac Pitman & Sons, London. At the outset, in order to avoid misunderstanding, it is essential to point out that the lumen values represented by the Lumens curve shown in Fig. 3 are solely those of the source of white light; they do not indicate the light value of colored light that may be produced by passing white light through .a color filter.

In Fig. 1, which shows a preferred form of the invention, |00 and IIJI represent the conductors of a supply circuit for the operation of a fourcolor lighting system employing a source of white light and sources of red, green, and blue light, with which the present control apparatus is associated. Across this supply circuit is connected the winding of an auto-transformer the movable contact member 2 of which is connected to the lamps of the lighting system, the mode of connection of which will presently be fully described. For convenience, the conductor |00 is referred to hereinafter as the live side of the supply circuit, and conductor I0| as the neutral or grounded side thereof, but it is to be understood that the control system will Work equally well if those conditions in the circuit are reversed.

The control apparatus employs a plurality of low pressure, small displacement switches, as, for example, Micro-switches, which are designated A to F, inclusive, in the figure. The upper contact points 3 of switches A, C, and E, are connected to conductor |09 of the lighting circuit. The lower contact points 4 of the switches A, C, and E, are connected to the conductor 53 which, in turn, is connected to the contact member 2 of the auto-transformer; and the movable contact members 5 of each of the switches, A, C, and E, are connected to the upper contact members 6 of each of the switches B, D, and F, respectively. The lower contact points 1 of each of the latter switches are connected to conductor 45 which, in turn, is connected to contact point 8 of a manually-operated switch 9 which is associated with the white lighting circuit. The movable contact members I0 of each of the switches B, D, and F, are connected to the red, green, and blue lamps, respectively. Associated with the movable contact members 5 of switches A, C, and E, are cams, as II, I2, and I3, respectively, and similarly associated with the movable contact members I0 of switches B, D, and F, are cams, as |4, I5, and I6, respectively, said cams serving as controlling means for the switches. While the two groups of cams are shown mounted upon separate rotatable shafts (indicated by the dot-and-dash lines), such showing is merely for the sake of clarity since it is preferable to mount all cams upon the same shaft, such as 30 in Fig. 4. A color chart, as 46, and an indicator, as 3|, in Fig. 4, will show the hues of color throughout the range of colors produced by the color lighting system during the rotation of the shaft 30 through the angular distance of 360. Each of the cams, II, |2, and I3, has two operating surfaces, and each of the cams, I4, I5, and I6, has one operating surface, the length of the operating surfaces and their relative positions in a preferred embodiment of the invention being as shown in Fig. 2. The white lamp is connected to the movable contact member Il of the switch B, the lower contact point I8 of which is connected to conductor |0I representing the neutral or grounded side of the supply circuit. Each of the circuits may be protected by circuit breakers,

aanwas such as '40 and 4|-, .or by switch-.fuses in accordance with conventional practices, if desired.

The manner :in which `t'he `control circuit :of Fig. 1 .is operated to select sources of flight and to regulate their intensi-ty, vwill be `described 'fi-rst as limited to the -use foi sources of colored fliglfit solely, and thereafter fa description will `be given of the mode of .operation of the circuit to effect the production fof pastel `hues :and pif-white colors.

Referring Ito the graph, Eig. .2, which shows by the darkened areas the Stime of operation and the duration of operationof each of the vswitches Ato F, inclusive, lbythefcams lil to I 5, inclusive, it will be seen that Vat the beginning of the Ycolor cycle olf 360, switches A, C, Aand F, 4are then Yoperated, having previously .been operated by `the cams ifi., 12, and i6, respectively, `associated therewith, and the switch 3D will be operated by the action of the cam i155. Accordingly, at that instant contacts 4 of 'switches A and 'C will be closed and likewise contacts Ei -of 4switches iD and F. Through contact f6 of switch F a 'circuit will be closed which will 'extend from the vconductor 500 to Vconductor l! of the supply Icircuit fand will include contact 3 of switch E, contact 6 of switch F, and the blue lamp, which will produce blue light which will be 'of maximum intensity since the `voltage applied thereto is the full linevoltage, Through the operation of Aswitches `C and D a circuit is established that extends from the movable contact member 2 -of the autotransformer -to conductor 10i yof the supply circuit vand includes conductor 53, contacts 4 and of switches C kand D, respectively, and the green lamp, thereby applying Vthe dimmer Voltage to that lamp. The switch AA remains operated through the 4angular distance of about 15 and then is released. This prolongation 'of the time of operation of switch A is to prevent the connection 'of the red lamp directly across the supply circuit IDU-IBL and the undesired produc tion of a flash vof red light 'of full value, which would be the result if the release of switch A occurred prior Yto the release of switch B.

Referring to Fig. 3, Ait will be seen that at the beginning of the cycle the dimmer voltage is a minimum, viz., volts, and in consequence thereof, there will be substantially no illumination produced by the `green lamp. As the Acontact member 2 moves `along the winding vof `the auto-transformer, the Voltage increases as shown in Fig. .3 and reaches the full line-voltage at '60 of `the full. color cycle of 360 as represented by the color chart shown in Fig. v9. It will be noted that throughout the period in which the intensity of green light has been gra-dually increasing the blue light has remained constant at maximum intensity. Accordingly, there will be a merging of those colors, the blue pred'ominating `during the 'early part of the period vof time until the green light reaches its Amaxi-mum at 60, when green light and blue light will be at full intensity.

Referring again to Fig. 2, it will be seen that shortly before the v60 point is reached, the Ycam l2 releases switch C while switches D and remain operated. Shortly after the release of switch C, switch E will lbe operated by vcam I3. It is desirable to mention that each of the vearns operating switches A, C, and E, is 'designed to n'ect'ed to the dimmer when its `voltage Iis maximum. Upon the-operation yof lswtch E a .circuit will be closed that will extend from the contact member -2 of the dimmer to conductor 10| and will include conductor 53, contacts 4 and Vl of switches E and F, respectively, and the blue lamp, thereby y'connecting that lamp to the dimmer circuit. Upon "the release of 'switch C its contact 3 is closed, and since contact 0 of 'switch D remains closed, the green lamp will be connected directly across the supply circuit. The net result is that both colors, Viz., blue and green, are still present in the illumination at almost identically the same `strength .as before those changes occurred. ff the Iswitches are `of snap `action type, as, for example, Micro-switches, fthe change in the connections cannot be discerned by `the eye because the lamp fcircui-t is Abroken during an extremely short period, approximately 1/200 of a'second, and the lamp filament does not lose al1 its heat in that time. Referring again to Fig. 3, Iit will be seen that from onward, green light is at full intensity whereas the intensity of blue is diminishing; accordingly, green will domi-'- nate throughout that range, producing shades of blue-green, and that condition will continue until the switch F releases at lthe point .in the color cycle when blue vanishes.

'Shortly before the 120 Ipoint in the color cycle is reached, switch A will be operated, and at the 120 point switch B will be operated, 'thereby connecting the red llamp to the Adimmer at the point of minimum voltage. Switch D remains operated at 120, which maintains the green lig-ht at maximum intensity. Switch F will be released at that point, 'as mentioned before, and switch E will be released 'shortly thereafter, `thereby disconnecting the blue lamp. Thereafter the dimmer voltage will rise and the intensity of red light will Iincrease, reaching maximum light value at of the color cycle. Consequently, throughout the period Vfrom 120 to 180 lthe hues of color will be a combination of 'green and red ranging through yellow-green to yellow.

Shortly before the 180 point is reached, `switch A is released, and shortly -beyond that point switch C is operated. At 180 switches .13 and D remain operated. The continuance in operation of switch .B after release of switch A connects the red lamp across the supply circuit i00--lil which applies the full line-voltage to that lamp and 'thus maintains the intensity of red rillun'lination at maximum light value throughout the range `from 180 to 300. The operation of switch C andthe continuance in operation of switch D connects the green lamp to the dimmer, the Voltage 'of which is, as shown in Fig. 3, gradually di minishing, reaching its minimum at 240 whereupon the green light vanishes. In the period between 180 'and 240?, the illumination will be a combination of red and lgreen light in which red will predominate, thereby producing hues of color ranging from yellow through orange to red. A 240 'switch D will be released and 'switch C shortiy thereafter. Shortly ybefore the 240 point, switch E will 'be operated, and at 240 switch F will be operated, and switch B remains operated. The :operation of switches E and F connects the blue lamp to the din-'liner Aand by the continuance of operation of `switch B the red Ilamp ree mains connected across the supply circuit. Accordingly, from 240 to 300 red will be at maxi-- mum intensity and blue will rise to the 'maximum light value at 300, thereby producing com binations of red and blue in which red will predominate. Switch E will be released shortly before the 300 point is reached, and switch A will be operated shortly thereafter, thus effecting the connection of the blue lamp across the supply circuit and the red lamp to the dimmer, the voltage of which is diminishing. Accordingly, in the last period of the color cycle, there is a combination of red and blue, in which blue will predominate. It should be noted that at 60, 180, and 300, which are points of maximum dimmer voltage, the cams are designed to provide separation in point of time between the release of one of the switches of the group A, C, and E, and the operation of another switch of that group, this separation, which may be of the order of 6 to 10, being desirable because it ensures the disconnection of one lamp from the dimmer before the connection thereto of another lamp, thereby preventing the overloading of the dimmer.

During the course of operation of the control apparatus just described, only the deep colors, red, green, and blue, have been employed in effecting the range of hues of illumination that is produced by the combination of those colors. In order to extend the range of hues of color, as, for example, to produce pastel hues, it is necessary to combine some white light and/or light of the complementary color with the deep colors previously mentioned, the intensity of the white light thus introduced being preferably about 10% of the lumen value of the white source at the full voltage normally applied thereto. The combining of white light with colored light is effected, in the circuit of Fig. 1, by the closing of the contact between the movable member I1' of switch 9 and the contact point 8 thereof. That operation not only introduces white light into a combination of colored light, but also automatically adjusts the intensity of the white light thus introduced., that adjustment in intensity of white light being effected by a reduction in the Voltage applied to the white source in a novel manner which will now be described.

It will be noted that during the operation of the control circuit, as previously described, one of the colored lamps is, at any instant, connected directly across the lighting circuit so that the full line-voltage will be applied thereto, another colored lamp is connected to the dimmer the voltage of which varies cyclically between a minimum and a maximum, and the third colored lamp has no Voltage applied to it, such being the condition of the red lamp during the period from to 120, the blue lamp during the period from 120 to 240, and the green lamp during the period from 240 to 360 of the color cycle. Since those idle lamps represent electrical resistance, use is made of them to reduce the voltage across the white lamp, the manner of doing which is as follows:

When the movable member l1 of switch 9 is operated upwardly so as to close its Contact 8, the white lamp will be connected through contact 8 and conductor 45 to contacts I of the switches B, D, and F. Referring to Fig. 2 it will be seen that during the period from 0 to 120, switches D and F are operated and in consequence their contacts "l are open, but switch B is not operated during that period and consequently its contact 1 is closed. Accordingly, the red lamp will be connected in series with the white lamp W and the dimmer, and since both lamps have the same resistance value, the voltage applied to each of those lamps will be one-half of the dimmer Voltage. In consequence the illumination given by the white lamp is markedly reduced, as shown by curve Y of Fig. 3, the maximum being about 10% of the full lumen output of the lamp at its normal voltage of volts, which amount of white light has been found to be satisfactory for combining with colors to produce desired hues of pastel colors. It is of course obvious that in a circuit such as that shown in Fig. 1 in which a colored lamp is connected in series with a White lamp to reduce the intensity of illumination of the white lamp, the colored lamp will also be activated. In a four color system employing white, red, green, and blue sources, the lamp that at a given time is connected in series with the white lamp, also has a pastelling effect, the reason for this being that the color of the lamp in series with the white lamp is the complementary color of the hue produced by the other two colored lamps. For example, if red and green lamps are connected to the dimmer and to the line, respectively, the illumination of those colors will be equal in intensity when the dimmer voltage equals the line-voltage, and the resulting hue of that combination is yellow. That color is the complementary color of blue, which is the color of the lamp then in series with the white lamp. Accordingly, the light from the blue lamp will contribute to the pastelling of the other of said colors. Upon referring to Fig. 3, it will be seen that during the middle of the period from 0 to 120 the control apparatus will effect the production of pastel hues by the introduction of a small amount of varying white light supplemented by the complementary effect of a small amount of varying red light in the manner above described; similarly, during the period between 120 and 240 the blue lamp will be connected in series with the white lamp and thus will contribute to the pastelling; and in the period from 240 to 360 the green lamp will be similarly connected and will function similarly to the red and blue colors. Hence, at the midpoint of each of those periods, that is to say, in the region in which the rate of change of the voltage curve is least, the illumination resulting from two selected deep colors (red and green in one instance, blue and red in the second, and green and blue in the third) will be modified not only by the addition of White of low intensity but also by the complementary color of the hue resulting from the selected pair of colors so as to produce a range of pastel hues which theoretically are infinite in number.

From the foregoing description it will be apparent that by means of the novel control arrangement shown in Fig. 1, it is possible to control by an apparatus employing a single dimmer the intensity of light produced by four distinct sources simultaneously, at values of illumination that differ widely; for example, in the range between 45 to 50 of the color cycle there would be present in the illumination produced by the color lighting system, blue light of maximum intensity, green light approaching maximum intensity, white light approaching 10% of the lumen value of the white source at full normal voltage, and red light (the complementary color of the resultant of green and blue) at a light value less than that of the white light.

When it is desired to produce a range of tinted whites, instead of pastel hues, it is necessary to control the color lighting system so that white will predominate in the illumination, the deep color being subordinate thereto. This illumination effect may be accomplished in the apparatus shown in Fig. 1 by operating the movable contact member I1 of switch 9 downwards; so: asta close its contact |585, and thereby connect the white lampdirectly between thev movable contact memb er 2 of the dimmerand` the neutral or grounded side of theA line |01?. When the white lamp is thus connectedthe full. voltage of` the. dimmer will be appliedi to that. lamp, and the intensityv of; white illumination:inilumenswills range from, Oto; 100%.

'Ehe eiiect. to theeye when thewhite illumination exceedszsay 25 of its full value'istha.t of white illumination tinted. by whatever combination of deep colors may. be selected by the operation of the switches shown in Fig.` l.` The off-white hues resulting from the` combining of' intense white light' with deep colors. aree designated: infv Fig. 9: in the segmentsv within, the inner circle of.v the chart as Cold Whites, Warm Whites,l and Flesh Whites," the Cold` Whites being those in'Y which the tinting is effectedV by the combination of :blue and green light; theY Warm- Whites being those tind. by the combination of; greenand red; and the Fleshi Whites being thosetinted by` red and blue in combinationrEhe combinations of deep colors. producethe-hues. that are indicated upon the outer.l circle of. theI chart and' those hues give tothe intiensewhite thetints that are indicated upon the segments within the inner circle. It will, of course, be` understood thaty in thev production ofoewhite lightthenon-activated color source', whichin` pastelling is connected in series with the white lamp; is entirely disconnected therefrom byf the opening of`contactil of s-witch and therefore hasno effect in theproduction of white light.

Fig. 4 showsoneform offthe'apparatus for ccntrollingthe voltage and also the connections in the circuit l'iereinbeforel described. The apparatus includesza driving shaft to which is xedly attached a pinion 2|-, a crankA Z2, and a knob 32, by whichthe shaftv may beI rotated manually. A crank-pin23 is attached" to the crank, the mode of attachment being such` that the radia1 distance of the pin-fromth'e center of rotation of the crank may be adjusted at. will. arm 2d which is. mov-ably connectedtofthe crank-pin has at its` outer endn aI rack 25".` which.' meshes-with' a pinion 25 that-isconnected`=to a-shaft`21, t'owhic'h is fasteneda contact member- Zwhich-is i's'contact with the winding 59` ofthe dim-mer orother voltage-varying device 53; The contact member makes Contact with-the successive turns ofi the winding 59 when the shaftA 2'Iis:rotated' in accordance' with the forward and-backward movements ofthe arm 24i and` appliesthe dimmer voltage tothe lamps' shown in Fig. l. The pinion 2i meshes with a gear 29swhich isfiixedly mounted upon theshaft 3t'lupon which isf also mounteda plurality of cams l lv to i9, inclusive. Each of the cams makes contact with the movablemember 5 of oneof the switches A to F, inclusive. The-shaft VSvalso-carries pointer' Sil, which, in thelcourse ofoperation offthe apparatusmoves acrossA acolor chart` 46, shown in fragmentary form in Fig. and fully in Fig; 9,' which may be mounted withinor uponthe casing in which the apparatus is installed; rlhe length of each of the two` operating surfacest or projectionszupon eacliof the camsfA, C', E, as showndn Fig. 2, may be of'fthe orderoff'lfl7 to 73; andthe projections upon cams B., D; and may be 2MP-in. lengthz asshown in that ligure. rlhecams aremounted upon the shaft. Stifsox that those;- surfaces orspiojections willroomeinto play at the.; points upon the color cycle. indicatedinithat gure-of the drawing.

The mode of operation of the controly apparatus to produce a desired hue of color by the lamps controlled thereby is as follows: The knob 3-2- is tur-.ned until the pointer 3 l., associated. with the color chart ilo, is adjusted toV indicate the desired color; The turning of. the knob 32 simultaneously effects thev rotation of the gear 29 and the movement of the arm 2li. rEheY rotation of gear 29 causes the cams Il to It, inclusive, to rotate, and. their movement effects the operation of,y the switches A to F, inclusive, in. predetermined order as shownlin Fig. 2. The movement ofA thearm 2tadjusts the position of the contact member 28. upon the winding 5e of the dimmer. .Sincethe arm 24, the pinion 2l, and the gear 29 moves simultaneously, there is obviously a dennite relationship between; the instantaneous values` ot the dimmer voltage. and the. electrical connections of the-lampv circuit which are controlled by the'cams upon the shaft 3i?` to which the gearl 219 is attached- That relationship is important becauseitisby virtue of it that the same wide rangeof' colors shown on the chart of. Fig. 9A may be reproduced again and again by the lighting control system. in which. this. invention is embodied.. When the shaft 2-makes one revo1utionthe. contacter 28 of the dimmer will be moved from. one' terminal of the dimmer winding to the.- other terminal thereofy and backA again to. theiirst terminal, thereby causing the voltage appliedito. a given lamp to vary through a complete cycleof voltagaas shown in Fig. 3. During thattime the gear 2Q wiilbe-moved by the pinion 2i; through one-third of acomplete. revolution sincethe ratio of. the-gear to pinion, in the case assumedi for illustratingv the invention, is three to:E one. Accordingly; the pointer 3l which is fastenedtofthe shaftl 36 will move through 120 of the;v full color cycle ofthe chart Q6, and thereafterV will move through the same angular distanceA for each. completerevolution ofthe pinion 2l', andi fon thef-ull 360 ofy the; color cycle there willbefthreecycles of dimmer voltage as shown by= Figs-'.2 and 3; When thecams are correctly proportioned and properly positioned upon the shaftf3,.they Willaoperate andrelease the switcheszA to Ffat'the times indicatedinlFig2 and will maintain them operatedduring the periods indicated. Since thecams-and the dimmer are controlled byA the. same controlling: means, viz., the knob: 32' and they shaft; 20 and since thev ratio off the'l pinionf to thefgear 29 is fixed, the relationship between"v th'e dimm-ervoltage-` and the action ofthe" camswis' likewise: fixed so that the same desiredhue-of' colorvmay be obtained, over and over,` by` merely setting the pointer 3l at the point upon thel chart-416' that shows the desired hue. When the pointerl is'- thus set, the proper switchesewillhave beenA operated'to connect one of thescoloredilamps-to the dimmer, anothercoloredilampaoross` the` supply circuit', and in the case of" pastelV shades, the thirdf colored light in series with-the-white lamp andfthe dimmer;v and the-voltage off` the dimmer` is automatically adjusted to produceilight ofi theproper intensity or light value that when combined with: light fiom\-the.source. connected across the supply circuit'..wi1l create the. desired hueof:y color. For thev sake.y off clarity, the.` electrical connections havexbeenk omitte'd'from'Fig. Li, but it is torbe vunderstood thatftheV apparatusshown in the latter figure; may bei. connected` either? in the manner shownfinEig, 11 orlrig; 5'; the latter of.- which-will presently; be described.`

Fig. inA shows ai modification.` of. the arrangel 1 ment of the cams for the control of the Microswitches by which six switches may be operated by two cams instead of six cams as in the arrangement of Fig. 4. The cam 64 has thereon two raised surfaces which coact with the movable members of switches A, C, and E, to effect their operation, the length of these surfaces and the spacing being that indicated in Fig. 2. The cam 65 has thereon a singe raised surface 240 in length as shown in that ligure which controls the operation of switches B, D, and F. When those cams are correctly positioned upon the shaft 36, the operation of the switches and the circuits controlled thereby will be similar to that `shown in Fig. 4 and described hereinbefore.

The arrangement shown in Fig. 5 is a modication of that shown in Fig. 1, the modification consisting in the use of two white lamps which may be connected in parallel, when greater intensity of white light is desired, or in series with each other to cut down the voltage supplied to each lamp when it is desired to reduce the intensity of white light. In the circuit shown in Fig. 5, the switches A, C, and E, are doublethrow, double-pole switches, preferably of the Micro-switch type similar to those shown in Fig. 1; the switches B, D, and F, are single-pole, single-throw switches, preferably of the same type as the switches A, C, and E; all said switches are mounted preferably upon the same shaft, as

shown in Fig. 4, but they may be mounted upon separate shafts as mentioned hereinbefore. The switches A to F, inclusive, control the selection and actuation of the sources of colored light: red,

green, and blue, the manner of doing which will 'i presently be described. When the switch I9 is operated to the left (as shown in Fig. 5), two white lights, WI and W2, are connected in parallel -between the contact member 2 of the dimmer 28 and conductor IUI of the supply circuit, the connection including the left-hand contacts of the switch. Upon the movement of the members 32 of that switch to its right hand contacts, the white lights will be connected in series with each other, which, as shown by the curve Y in Fig. 3, will cut down the illumination given by each of the white lights to about 10% of the maximum intensity in lumens that each is capable of producing at its normal voltage, e. g., 12'0 volts.

The manner in which the circuit of Fig. 5 operates to control the color lighting system is as follows: It will be assumed that the movable members 32 of the switch I9 are upon the right hand contact points of the switch which connects the white lights WI and W2 in series with each other, and that the knob 32 has been turned sufficiently to effect the operation of the switches C, D, and F, as shown at the left hand side of Fig. 2. The operation of switches C and D applies the dimmer voltage to the source of green light, but no illumination will result therefrom, since, as shown in Fig. 3, the voltage of the dimmer at that instant is the minimum. Since switch F is also operated at that time, the full line-voltage will be applied to the source of blue light which will produce illumination of maxi mum intensity. Since the white lights, WI and W2, are also connected to the dimmer, no illumination will be produced by them at that instant, therefore, at the beginning of the color cycle the illumination will come from the blue source, but as the knob 32 continues to move through the range from 0 to 60, the intensity of the green light will gradually increase and will reach its maximum at 60; the intensity of the white light Cil will also increase and reach its maximum at 60; but since the white lamps are in series (the vo1t age across each lamp is one-half the normal voltage) the intensity of the white light is greatly limited, as shown by curve Y. This effects the creation of pastel hues as described hereinbefore with reference to the circuit of Fig. 1. Near 60 of the color cycle, as shown in Fig. 2, switch C will be released by the operation of cam I2, and shortly thereafter switch E will be operated so that, as shown in Fig. 2, switches D, E, and F, will then be operated. The operation of switches E and F connects the blue source of light to the dimmer, and the operation of switch D connects the green source across the line. Since the dimmer voltage falls throughout the range of 60 to the intensity of the light from the blue and the white sources will diminish thus leaving the light from the green source dominating at the end of the cycle. In similar fashion, the several sources of colored light will be activated by the operation of the switches under the control of the cams in the sequence shown in Fig. 2, and the resulting deep hues of color will be pastelled by the relatively small amount of white which is represented by curve Y of Fig. 3. When it is desired to increase the intensity of the white light, the switcharms 32 are moved to the left hand contacts of the switch I9 thereby connecting the lamps in parallel between the dimmer and the neutral side IOI of the supply circuit. This effects a marked increase in the intensity of the light given by the white lamps, as shown by the curve X in Fig. 3, which reaches its maximum at 60. Thereafter the intensity of white illumination diminishes up to 120 of the color cycle, when it becomes practically nil. The dimmer voltage cycle is repeated -between 120 and 240, and between 240 and 360 as shown in Fig. 3. The intensity of the white light is so great as to dominate the illumination, the deep colors serving merely to tinge the white light.

.The resulting illumination therefore is a range of near-white light.

In the foregoing description of the control apparatus disclosed in circuit form in Figs. 1 and 5 and in mechanical form in Fig. 4, only manual operation of the apparatus has been mentioned, but it is not limited to that mode of operation. The apparatus may be operated either manually or by power, as by an electric motor or other suitable means as is shown in Figs. 6 and 6a. The 'arrangement Ishown in Fig. 6 provides not only for the selection of particular hues by manual operation of the apparatus but also makes possible, by a motor drive, the continuous production of the entire range of hues of color in sequence. As there shown the shaft 20 to which kis fastened the pinion 2|, which is normally in engagement with the gear 29 for manual operation of the apparatus, is arranged to be moved longitudinally, as shown in the figure, so as to move the pinion into engagement also with the gear 31 when continuous operation of the apparatus is desired. When the pinion 2I is in engagement only with the gear 29, operation of the control apparatus is eifected manually by rotation of the knob 32 precisely in the manner heretofore described. When continuous rotation of the cams is necessary in order to produce the entire range of hues of color in sequence, shaft 30 may be driven by a motor such as 38 in Fig. 6a, or other source of power which may be connected directly to the shaft 30 or indirectly, as shown in that gure, by a belt or chain drive. The drivingforce isapplied to la sprocket, as 34, which fastened to the shaft 36 to which is also fastened the gear 31, which, as mentioned, is normally disengaged from the control apparatus. In order to render the gearY 31' effective to drive the cams and the arm that controls the autotransformer, the shaft 28 is moved inwardly, that is, to the left as shown in- Fig. 6, tosuch extent as to lbring the pinion 2| intoengagement also with gear 3?-, Thereupon the continuous rotary movement of theA gear 31 will be transmitted through the pinion 2| to the gear 29, which, in turn, will effect theV continuous rotation of the cam-s H to I6, inclusi-ve, and the operation of the switches A to F, inclusive, as well as the oscillatory movement of the arm 24. When continuousl operation of the control apparatus is-- no longer desired, it may be stopped by withdrawing the pinion 2l from engagement with the gear 31. engagement with the gear-29 forl manual operation ofi-the apparatus.

In order to prev-ent the pinion 2| from becoming disengaged from the gear 31 while the apparatus is being driven by the motor, holding means has been provided which prevents the shaft from moving toward the right, as shown in Fig. 6, after it has been pushed to the left to effect the engagement ofthe pinion and said gear. The holding means there shown includes a member 49 to whichra knob50 is fastened, said member extending throughthe wall 52 of the casing and being` move-bly supported thereby. The member 49 has` an arm 41 rigidly fastened thereon whi-ch, as shown in enlargedform in Fig. 6b,

has a notchV therein near its outer. end, the width of the notch being slightly greater than the diameter ofthe shaft 2B topermit engagement of the shaftby the` arm, the purpose of which will presently -be made clear. Between the knob 32 and the wall `52 ofthe casing is a, spiral spring 5i which encirclesthe shaft, said spring being intended to apply the force requiredto withdraw the pinion 2i from engagementwith the gear 31 upon the disengagement of the locking means. A collar 418 is securely fastened to the shaft 2U the cylindrical face offthe collar-being sufficiently broad-to permitsthe arm 41to resty thereon after the pinion has been withdrawn from engagement with'the gear 31. Thecollar is sopositioned upon said shaft and the width of its cylindrical face is such that when thepinion 2! has been moved by the shaft into engagement-,with the gear 31`V the arm 41 wi-ll be brought into engagement with the shaft 20 at a point upon said shaft between the collar 48 and the wall 52. The collar dil will then -be firmly held against the arm 4-1 by the action ofthe spring `5l, thereby preventingY theshaft fromv moving toward the right, as shown in Fig. 6. Accordingly, the pinion 2i will be securely held in engagement with the gear 3?'. When it is desired to withdraw the pinion from engagement with the gear 31, the knob 5D is turned in clockwise direction thereby causing the arm-t1to move through sufficient angular distance to permit the collar 48 to pass thereunder when the shaft '20 is drawn to the right (as in Fig. Si) by the action of the spring 5|. The form of locking device shown inthe drawing and describedherein isk purely by way of illustration since itis obvious that otherV forms of locking devices within the scope of the present invention may be employed to effect the same result.

When continuous operation of v a plurality of control units such as 60 to v62,- inclusive, is--de- The pinion will, thereafter, remain in sired by a single source of power, an arrangement such asV is shown in Fig. 6a maybe employed; In that figure, whichis a rear view of a group of. three units, a motor, represented by 38. is shown mounted upon the topmost unit and connected.l to the control mechanism in each of said: units by either a belt drive or a chain and sprocket drive, but the motor may be placed in other positions in relation to theunits, if desired. Obviously, any number of units desired may be driven by a single motor of suitable power, but in order tokeepa plurality of units in alignment a suitable framework is necessary, such, for example, `asY is represented by dot-and-dash lines in Figi 6a.

Although themotor is shown in Fig. 6a connect-edtdall` units, it should not be implied that all units must. be operated simultaneously, As mentioned hereinbefore, each control unitY may be readily adjusted for operation, either manually orsby motor drive, as desired, by shifting the positorrof the pinion in the unit. For example, if it is desiredl to maintain constantly a denite hue of color by the light sources controlled by one of theunits, for example, 6|, and at the same time to produce repetitively the range of colors of the light sources controlled by the other control units, Sil and 62, that result may be obtained by maintaining the pinion 2l of unit 6| out of engagement with thegear 31' and, at the same time keeping the pinions of theother units in engagement with the gears 31 of those units. The control unit 6l would, ofcourse, -be adjusted to effectthe production of the desired hue of color by the lights controlled thereby in the manner fullydescribed hereinbefore.

Figs. 1 and '1c show. other ways in which the normally inactivated source of colored light may be employed in-the circuit shown in Fig. 1. The arrangement shown in Fig. 7 shows the manner inwhichthe normally inactivated source of color may be employed to pastel' the two activated sources of color in athree-color lighting system. As shown in thatl gure, a resistance 54 is profvided, the magnitude of which is sufficient to reducethe light` value of a colored source of light to'a desired level` The resistance 54 is connected between contactmember 2 ofthe dimmer and the movable member |1a of the switch 9a. When the switch is closed by moving the member |1a into contact with Bc, the normally inactive colored lamp, such as the red. lamp indicated, is connectedto the dimmer, the connection including the contacter 2, resistance 54, switch 9a, conductor 4,5; contact 1' of switch B, and the red lamp. Accordingly, the red lamp would be activated, but at-alowerf intensity than would be the case if the lamp were connected directly to the dimmer. Sincevredis the complementary color of the hue resulting., from blue and green (which are the normallyuactiyated colors when red is normally inactivated), the red lighth'as apastelling effect upon the resulting hue of blue and green. The 4arrange-ment shown in Fig. 7a provides for the connection of a normally inactivated lamp in series-,withthe resistance to pastel the resulting hue of the other two colors, or to use the normallyinactivated lamp as a resistance to reduce the intensity of a white source of light in pastelling thedarkerhues. When the switch 58 is operatedto close the contact 55'--5S, the normally inactivated'Y lamp R will be connected in series with the resistance 54a andethereby will become activatedbut 'at a low light value. When it is desred to usethe inactivatedcolor source as a resistance to reduce the intensity of the source of White light, the switch 58 is operated to close its Contact -5'L and switch 9 is operated to close its contact I18, thereby connecting the normally inactivated source of colored light R in series with the source of white light W. If it is not desired to reduce the intensity of white light, the switch 9 is operated to close its contact l'1-|8, thereby connecting the white lamp directly between the dimmer and conductor 10| of the supply circuit thereby increasing the range of nearwhite tints. The term normally inactivated" as used herein to characterize a source of colored light, means that the light source so -characterized is one that, during the normal operation of the apparatus, is at a given moment not connected to any source of potential; for example, in Fig. 1 (when operated 'as a 3-color system) the red lamp is inactivated at 0 when the green lamp is connected to the dimmer and the blue lamp is connected to the power line; similarly, the blue lamp is inactivated at 120 when the red lamp is connected to the dimmer and the green lamp is connected to the line; and likewise, green is inactivated at 240 when blue is connected to the dimmer and red is connected to the line. When the normally inactivated color source is connected in series with the white source as in Fig. 1 (when operated as a 4-color system) or in series with a resistance las in Figs. 7 and 7a, it,

of course, -becomes activated by the voltage of said dimmer.

Figs. 8 and 8a show other arrangements by vwhich the intensity of White light in the circuit shown in Fig. 5 may be controlled. In Fig. 8 the white lamp W3 is shown connected in series with resistance 33, the magnitude of which is suicient to reduce the maximum light value of the source W3 to the desired level. A switch may be provided to shunt the resistance 33' when it is desired to apply the full dimmer voltage to that lamp. Fig. 8a shows another way of controlling the intensity of white light from the source W4 which consi-sts in connecting one side of the lamp to a tap on the winding of the auto-transformer,

the tap being so placed that the maximum voltage applied to the lamp by the transformer will not exceed a desired value. A switch BB is provided to close or open the circuit of the lamp W4 as desired.

While the aforedescribed methods of controlling the intensity of the white light may be employed, the Ipreferred method is that in which the normally inactivated colored lamp is employed as a resistance to limit the voltage applied to the white lamp and, in consequence, to reduce the intensity of illumination produced thereby.

While the voltage-varying device has -been represented in the various figures as an auto-transformer and has been so referred to hereinbefore, it is to be understood that other forms of voltage-varying devices may be employed, such as (but Without limitation) saturable reactors, electronic devices, or resistors. The term dimmer" as used herein is intended to be generic to all such voltage-varying devices.

It is to be understood that the term "White wherever employed in the specification and claims, to characterize the color of light, is intended to mean a more desaturated color than the other colors employed in the lighting system, the Vdegree of desaturation ranging from that represented by a paler hue than the other colors 16 employed to desaturation, that is, pure white.

Furthermore, it is to be understood that the invention is not limited to the use of the specific colors of the sources of light mentioned hereinbefore and indicated upon the drawing. All of said sources may be of the same color or all white, or any combination of colors desired.

Though the invention has been described as embodied in particular forms and arrangements of parts, it is to be understood that it is not s0 limited but is capable of embodiment in other and different forms and arrangements Without departing from the spirit and scope of the appended claims.

What is claimed is:

1. In a control system for colored lighting, in combination, three electrical sources of colored light, each of the colors of which is approximately the complementary color of a hue resulting from the combination of colored light of the other two sources, an electrical source of light of paler color than those of said other sources, a dimmer, switching means to select a source of colored light and to apply the dimmer voltage thereto, said switching means being arranged to simultaneously maintain the application of a constant voltage to another of said sources of colored light and to connect the third source of coiored light in series with the light source of paler color and said dimmer.

2. In a control system for color lighting employing three electrical sources of colored light, each of the colors of which is the complementary color of a hue resulting from the combination of colored light of the other two sources, an electrical source of light of paler color than those of the other sources of light, the method which consists in selecting and activating two of said sources of colored light, and connecting the third source of colored light in series with the light source of paler color and activating said latter sources as thus connected.

3. In a control system for color lighting employing three electrical sources of colored light, an electrical source of white light and means to activate said sources, the method which consists in selecting and activating two of said sources of colored light, and varying the intensity of illuminating of said source of white light by connecting in series therewith the normally inactivated source of colored light.

4. In a control system for color lighting employing four electrical sources of light, and means to select and activate said sources, the method which consists in selecting and activating two of said sources of light, activating a third source of light and controlling the intensity of its illumination by connecting in series therewith a normally inactivated source of light.

5. In a control system for color lighting, in combination, three electrical sources of colored light each differing in color from the others, an electrical source of white light, a dimmer, switching means to select one of said sources of colored light and to apply the dimmer voltage thereto while maintaining the application of a constant voltage to another source of colored light, said switching means being further arranged to connect the third source of colored light in series with the source of white light and said dimmer and common means for actuating said rst switching means.

6. In a control system for color lighting, in combination, three electrical sources of colored l2? light, each of; the colors of which is approximately the; complementary color o1V a hue resulting fromY the combination of light fromthe other two sources of colored light,` a dimmer, switching means to select one of said sources of colored light and to apply the dimmer-voltage thereto while maintaining the application of` a constant voltageA to a second source of colored light, said switching means being further arranged to simultaneously connectA the, third source of colored light in series with said dimmer, said connection including means tov limit thev Voltage applied to said third source of light.

7. The combination defined by claim 6 characterized in that the number of operating cycles through which the dimmer voltage passesl to produce the full range of hues of the color cycle equals the number of sources of colored. light employed in the system, and further characterized by the interchanging of the connections of the first and the second sources of light with their respective sources of voltage when the dimmer voltage is maximum whereby the constant voltage will be applied to the :first selected light source and the dimmer voltage to the second selected light source.

8. In a control system for color lighting, in combination,l three electrical sources of colored light each of the colors of which is approximately the complementary color of a hue resulting from the combination of light from the other two sources of colored light, a dimmer adapted to vary cyclically the voltage applied to each of said light sources in sequence throughtout, 360.o of a color cycle, each voltage cycle being equal to 120D of the color cycle, and. switching means to change the connections or the dimmer tothe color sources at approximately each 60 of the color cycle.

9. In av control system for color lighting, in combination, three electrical sources of colored light each of the colors of which is approximately the complementary color of a hue resulting from the combination of light from the other two sourcesof colored light, a dimmer, switching means to select pairs of light sources in sequence and to connect to theY dimmer one light sources of the selected pair and to connect to a source of constant voltage the other lightY source of said pair, the color combinations ofv the successively selected pairs being different, said switching means being further arranged to connect to said dimmer the source of light remaining after each selection of a pair of light' sources has been made, the connection including means to limit the magnitude of the voltage applied to the remaining source of light.

10. In a control system for color lighting employing three electrical sources of colored light each of the colors of which is .approximately the complementary color of a hue resulting from the combination of light from the other two sources of colored light, a dimmer and selecting means, the method which consists in utilizing simultaneously the three sources of colored light, applying to one selected source a voltage of constant value, simultaneously applying to the second selected source a voltage varying between less than 25% and 100% of the stated constant value, and simultaneously applying to the third selected source a voltage varying between less than 25% and 50% of the stated constant value voltage, the rate of change of the voltages applied to the second and third selected sources being the same.

11. In a control system for color lighting, in combination, three electrical sources of colored light each. of the colors: of which is approximately the complementary color of a hue resulting from the combination of light from the other two sources of colored light, .means to vary cylically the magnitude of a constant applied voltage and switeL ing means to connect each of the light sources in sequence to said voltage varying means, said switching means being arranged to maintain one of said light sources activated at fullv intensity and simultaneously to maintain a second light source inactivated while the third light source is simultaneously connected to said voltage Varying means, the periods of activation of the first mentioned light source and of inactivation of said second light source being staggered by a distance equal to one-half of a complete cycle through which the constant applied voltage may be variedV by said voltage varying means.

1L.. In a colored lighting system having a plurality of sources of colored light, a source of white light, a dimmer and selecting means, the method which consists in selecting simultaneously two sources of colored light, applying to one source a voltage varying continuously through a range of values, simultaneously applying to the secondy selectedsource a voltage of constant value and selectively connecting a third source of colored light in series with said source of white light and applying thereto said continuously varying voltage.

13.. in a colored lighting system having al plurality of sources of colored' light, a source of white light, a dimmer and selecting means, the method which consists in selecting simultaneously two sources of colored light,l applying. to the nrst selected source of light the dimmervoltage whichV varies cyclically through a range of Values, simultaneously applyingY to the second selected source of light a voltage of constant value equal to the maximum, dimmer-voltage, selectively connecting a third source of colored light in series with sa-id source of white light and applying thereto saidV dimmer-voltage, and interchanging the connections between said rst and; said second source of light and the sources ot voltage whereby the constant voltage will be applied to the rst selected light source and the dimmer-voltage to the second selected light source.

lll. In a system of color lighting employing four electrical sources of light, one of which. is white and the remainder colored, a source of voltage and means to Vary said voltage, the method of producing a range of pastel colors which consists in selecting two of said colored sources of light, applying a constant voltage to one of the selected sources, simultaneously applying a varying-voltage to the other selected source, applying a voltage to said source of white light and reducing its intensity of illumination by automatically connecting in series therewith the remaining source oi colored light.

l5. In a control system for color lighting, in combination, a plurality of sources of light, means to vary the light intensity of said sources one at a time throughout a given range of Values, a plurality of pairs of switching means each pair being associated with one of said sources, controlling means connected with all said switching means to selectively operate both switches of n one pair of said switching means and to connect to the intensity-varying means the source of light associated with the selected pair and simultaneously therewith to release one switch of a previously operated pair of switches, the source of light associated with said previously operated pair of switches being maintained activated.

16. The combination dened by claim 7 further characterized in that the controlling means is also arranged to connect two other of said sources of light in series with each other and with the light intensity-Varying means.

17. In a control system for color lighting, in combination, three electrical sources of colored light, each of the colors of which is approximately the complementary color of a hue resulting from the combination of light from the other two sources of colored light, a source of constant voltage, a source of varying voltage the maximum of which equals the constant voltage, switching means to select in sequence two of the sources of colored light and to connect the rst selected source of light to the source of varying voltage and the second selected source of light to the source of constant voltage, said switching means being arranged to effectively interchange said connections between said sources of light and said sources of voltage when the varying voltage equals the constant voltage, said switching means being further arranged to connect the third source of colored light to said source of varying voltage, said connection including means to limit the voltage applied to said third source of colored light.

18. In a control system for color lighting, in combination, a plurality of electrical sources of colored light, an electrical source of white light, a source of varying voltage, a source of constant voltage, switching means to select in sequence two sources of colored light and to connect one source of colored light to the source of varying voltage and the other source of colored light to a source of constant voltage, said switching means being arranged to effectively interchange said connections between said sources of light and said sources of voltage when the varying voltage equals the constant voltage, said switching means being further arranged to connect the non-activated source of colored light in series with said source of white light and said source of varying voltage.

19. In a control system for color lighting, in combination, three electrical sources of colored light each differing in color from the other, a source of white light, a voltage-varying device, three pairs of switches, each pair associated with one of said sources of colored light, controlling means to select and operate one pair of said switches and to apply the voltage of said voltagevarying device to the source of colored light associated with the selected pair of switches, said controlling means being arranged to maintain the application of a constant voltage to a second source of colored light and to connect the third source of colored light in series with the source of white light and said voltage-varying device.

20. In a control system for color lighting, in combination, a plurality of electrical sources of light one of which is white and the remainder colored, a dimmer connected to the source of r white light and arranged for connection in sequence to the colored sources of light, a plurality of pairs of switches each pair being associated with one of said sources of colored light, a plurality of simultaneously operated cams each oper- Aatively connected with one of said switches, said cams being arranged to operate both switches of one pair to effect the application of the dimmer voltage to the source of light associated therewith, said cams being also arranged to release one switch of a previously operated pair to apply a constant voltage to the source of light associated with said pair.

21. In a color lighting system, the combination comprising a power circuit, at least three electrical sources of colored light and one electrical source of light of paler hue, a single dimmer connected to said circuit, and a plurality of switches connected to said circuit and actuable to connect any one of said three sources to said circuit at full voltage, another of said sources in series with said dimmer and the third of said sources to said circuit in series with said source of paler hue and said dimmer.

22. In the combination of claim 21, a common operator for said switches and said dimmer.

ROLLO GILLESPIE. WILLIAMS.

vReferenees cited in the sie of this patent UNITED sTATEs PATENTS Number Name Date 1,682,566 Hunter Aug. 28, 1928 1,872,154 Masek Aug. 16, 1932 1,872,156 Masek Aug. 16, 1932 1,899,575 La Roque Feb. 28, 1933 1,931,799 Hunter Oct. 24, 1933 v2,220,4:15 La Roque Nov. 5, 1940 '2,225,994 Hunter Dec. 29, 1940 2,232,077 Rosecky Feb. 18, 1941

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