Патент USA US2500049код для вставки
March 7, 1950 ‘ ' F. c. WILLIAMS EIQ‘AL 2,500,049 APPARATUS FOR mans COLOR PRINTS Filed May 10, 1946' ' :5 Sheets-Sheet 1 2'.FIG. FIG.1 5-1 [email protected] ’ . "K ‘ INVENTORS BY 4am-m Mm March 7, 1950 2,500,049 F. c. WILLIAMS ETAL APPARATUS FOR MAKING COLOR PRINTS Filed May 10, 1946 3 Sheets-Sheet 2 so: Eu 0 Wm‘.. mm c. WILLIAMS FORDYCEM. BROWN mmwoxs BY W ' ATTORNEYS ' March 7, 1950 2,500,049 F. c. WILLIAMS EI'AL APPARATUS FOR mmc COLOR PRINTS Filed May 10, 1.946 3 Sheets-Sheet 3 FIG.5. FIG.4. FIG.-7. c N FRANKLIN C. WILLIAMS FORDYCE M. BROWN INVENTORS BY W/ 1/ ATTORNEYS 2,500,040 Patented Mar. 7,v 1950 UNITED STATES PATENT OFFICE 2,500,049 APPARATUS FOR COLOR PRINTS ' Franklin 0. William and Fordyce M. Brown, Rochester, N. Y., asslgnors to Eastman Kodak ~ / Company, Rochester, N. Y., a‘ corporation of New Jerley Application May 10, 1946, Serial No. 668,832 17 Claims. (01. 88-24) 1 . The present invention relates to photography, and particularly to an apparatus for making color The primary object of the present invention is the provision of an apparatus for compensating I prints. for variations in the exposure requirements in making a color print by the above-disclosed method and apparatus which might be intro duced by a change in the color sensitivity of the printing material due to an actual change in the emulsion sensitivity and/or an apparent change in sensitivity due to a change in the processing Speci?cally, this invention relates to an im provement in the method and apparatus for making color prints set forth in copending patent applications, Serial Nos. 668,800 and 771,068, ?led May 10, 1946, and August 28, 1947, respectively, in the names of C. M. Tuttle and F. M. Brown. The color printer set forth in these copending Procedure. applications, and known as a negative-integrator And yet another object is to provide an appa type printer, operates in the following manner: ratus, hereinafter referred to as a compensating unit; or compensator, which can be built into, The color negative is placed over a diffuse light source. An image of this negative is projected to form a part of, said color printer so that the onto a color-sensitive paper by a lens which can 15 printer so equipped will have its control auto: be successively covered by a red, a green and a matically compensated for variations in the ex blue ?lter. Light from this source and trans ' posure requirements introduced by any one or mitted by the negative also illuminates a photo all of the changes mentioned. electric cell in such a way that an integration Still another object is to provide a compensat of the negative’s transmittance is effected. When 20 ing unit for a color printer of the negative the red ?lter is over the projection lens a similar, integrator type referred to which includes means but not identical, red ?lter is also placed over for illuminating each of different color areas of the integrating cell. With such an arrangement a compensating chart, made by a given exposure > the intensity of the source is quickly adjusted through red, green and blue ?lters on the print until a predetermined ?xed response of the photo 25 ing material to be used and processed by the pro electric cell and system associated therewith cedure to be used, with a light of known intensity results and a ?xed time exposure is then given and of a color substantially complementary to to the printing material. The operation is then the area of the chart illuminated thereby, and repeated with green ?lters over, the lens and photo-electric means measuring the amount of photo-cell, adjusting to the same photo-cell sys light re?ected by each area. The photo-electric tem response, and finally with blue ?lters over means of the unit is connected to the photo the lens and photo-cell. ‘ electric integrating cells of the printer control The adjustments of the printer control (the system so that the output of the former when predetermined response of the photo-cell system measuring the amount of light re?ected by" a which determines the intensity of the colored 35 chart area when illuminated by a given color printing beam) are empirically determined. and light (red) is adapted to change the amount of are correct only for a given set of color sensitivi response required of the integrating cells of the ties of the individual layers of the multi-layer printer when measuring the intensity of a corre color sensitive printing material. If a change sponding color light (red) transmitted by the in any of these color sensitivities occurs as a re 40 sult of change in printing material or in process A further object is to provide a compensating unit of the type described in which the chart areas, the illuminating means therefor and the cells for measuring the amount of light reflected by said areas are so arranged and disposed rela tive to one another that only the light diffusely re?ected by said areas is measured by the cells. And yet another object is to provide a com 60 pensating unit in which the intensity of each of ing, the adjustments of the printer control must be revised. This means that every time a new batch of printing material is used which might have a color sensitivity different from that for which the printer is initially adjusted, or there is a change in the processing procedure (such as a change in processing solutions, the order of processing, etc.) which might cause a change in the apparent color sensitivity of the printing material, the printer must be readjusted ‘em pirically to accommodate any change in sensi tivity which might occur. This is a decided drawback which restricts the quality and the negative. ' . the chart area illuminating beams may be ad justed simultaneously by the same amount to vary the over-all density of a color print, or the intensity of the illuminating means for the re quantity of the output of the printer in question. I‘ spective chart areas can be individually adjusted 0,500,040 hated. shows identical yellow and magenta dye for the purpose of altering the color balance of a color print made on the printer. deposit densities, but an increase of 0.10 in den sity of the cyan deposit. The required revision of printer adjustment is one which will decrease the printing of the red sensitive layer of the The novel features that we consider charac teristic of our invention are set forth with par ticularity in the appended claims. The invention itself, however, both as to its organization and its methods of operation, together with additional objects and advantages thereof, will best be un derstood from the following description of speci?c embodiments when read in connection with the printing material by 108 0.10. One possible method of making this revision is by increasing the sensitivity of the transmission integrator of the printer by 10g 0.10 for red trans mission integrations. We have discovered how accompanying drawing in which, this can be done automatically and will now de scribe our invention in connection with di?erent Fig. 1 is a diagrammatic view, in perspective, of the essential mechanism and circuit organiza embodiments of the color printer shown in the above-noted copending Tuttle and Brown ap tion of one embodiment of a combined color printer and compensating unit constructed in 15 plication. We will ?rst consider the application of the accordance with the present invention, Fig. 1A is a wiring detail showing the hook-up present invention to an embodiment of the color printersuchasthatsh0wninl'1gs.iand6ofthe between the integrating cell of the printer and noted Tuttle and Brown applications. As shown the compensating cell of the compensating unit in Fig. i of the present application this embodi in accordance with the arrangement of P18. 1, ment of the printer comprises a standard projec Fig. 2 is a plan view of a color negative used tion printer having a “white" light source II. a to make the compensator chart used in the com carrier for negative ll, a projection lens II. and pensating unit of Fig. 1, Fig. 3 is a diagrammatic view, in perspective, means, not shown. for holding a sheet of multi layer color sensitive printing paper it in the focal of the essential mechanism and circuit organiza plane of the lens. A filter disk It is disposed tion Of a combined color printer and compensat between the negative and the lens and includes ing unit constructed in accordance with another, and preferred, embodiment of the present inven~ three ?lters. one each of red, green and blue, designated R, G and B, respectively, which may tion, be individualLv indexed into the printing beam Fig. 4 is a horizontal sectional view of a com transmitted by the color negative in the carrier pensating unit suitable for use in the arrangement to spectrally select separate colors from the beam shown in Fig. 3. for printing purposes. When making a color Fig. 5 is a vertical section of the compensat print, the ?lter disk is ?rst indexed to place the ing unit shown in Fig. 4 and showing the stage red ?lter R in the printing beam and the color for illuminating the yellow chart area by a blue sensitive paper is exposed to red light for a given light, time. Then the ?lter is successively indexed to Fig. 6 is a view of the type of compensator position the green and blue ?lters, G and B. in chart adapted for use in the compensating unit the printing beam and the same paper area is shown in Figs. 3-5, and successively exposed to each of these colors for Fig.7 is a wiring diagram for the three lamps a given length of time. When paper has been of the compensating unit. exposed to each of the primary colors for the se Like reference characters refer to correspond ing parts throughout the drawings. lected time. the exposure is completed and the print is ready for processing. As pointed out above, the adjustments of the negative-integrator type color printer referred 45 The printing time for each of the primary colors to are empirically determined and are correct only is ?xed and the intensity of the light source is for a given set of sensitivities of the individual varied in accordance with the color balance of the layers of the multi-layer color sensitive printing negative so that the paper is given the same expo material. If a change in any of these sensitiv ities occurs as a result of change in paper or pro cessing, the printer adjustments must be revised. sure for each of the three colors. 60 To do this. a light-sensitive cell it of the photo»emissive type is disposed adjacent the lens in a position which enables it to receive light passed by the negative. This cell, known as the integrating and measuring ing combination, relative to the old combination. cell, is alternately covered by red. green and blue or the one for which the printer is initially ad 55 ?lters in the same order as the printing beam. These revisions can be computed if the semito metric characteristics of the new paper-process justed are known. According to the present invention, one method of making such determinations of sensitometric characteristics consists of making sensitometer exposures on the printing material with red, green and blue light of such quality that each exposes only a single emulsion layer of the multi and for purposes of simplicity we have shown the cell covered by the same ?lter as cuts the printing beam for exposure purposes, although thisisnotactuallvthecaseaswillbeappreciated layer printing material. Bubsequent processing by referring to the above-noted Tuttle and Brown application. After a given color ?lter has been indexed over the lens and cell. red for instance. the cell integrates the red light transmitted by then results in isolated areas of cyan, magenta, and yellow dye deposits. The density level 0! these dye deposits should be somewhere on the The intensity of the printing source is then varied by means of rheostat l'l until the cell gives a sig straight-line portions of the printing material nalthattheintensitwofthelightissu?icient the negative and begins to measure its intensity. for printing purposes. Then the exposure of the dye deposits can be determined by a photo-elec paper by that color, red by way of example, is tric densitometer, using red, green and blue illu 70 started and maintained for a pre-selected time. This procedure is then repeated with each of the minants of such quality that the gamma of each green and blue ?lters indexed into the printing individual dye deposit of the paper as determined beam and over the integrating cell. by this densitometer is 1. Bay then that the com The printer includes an automatic control of parison of a new printing material with one cut rently in use, and for which the printer is ad- I‘ thetypeshownin?ghandcompletelydescribed characteristic curves. Now the density of these 2,500,040 5 , - 6 in the above-noted copending application. Only The compensating cell Ill is connected into so much of this control will be brie?y described herein as necessitates an'understandlng of the the ampli?er circuit of the printer to act as a load resistor of the ampli?er I03 which is handling the response of the negative integrating cell Ii 0! the printer. This hook-up is clearly shown in Fig. 1A. The sensitivity of the ampli?er is directly proportional to the load resistance. The resist ance of a photo cell is inversely proportional to its illumination. Therefore, the sensitivity of the 10 ampli?er is now inversely proportional to the illu mination of the compensating cell III, and the present invention. The rheostat I1 is adapted to be driven in both directions by a shaded-pole reversible motor MP. The direction of drive of this motor is controlled by a cam 6| which oper ates the switch 60 to alternately connect diifer ent ones of the shading windings CW and CCW of the motor into circuit. At the end of an ex posure with each color light the motor is con log sensitivity of the ampli?er is directly propor tional to the density of the paper dye deposits. a minimum value after which the shading wind The log intensity of the illuminant called for by ings are reversed and the motor drives in a di 16 the printer ampli?er is, therefore, inversely pro rection to cut the resistance out of the lamp portional to the density of the dye deposit. Be circuit. The integrator cell It integrates and cause gamma is 1, the intensity of the printing measures the intensity of the negative trans light has been made inversely proportional to the mitted light and when the intensity reaches a sensitivity of the paper, and exact compensation pre-selected value, as determined by the adjust is therefore effected. As will be apparent from nected to drive the rheostat II in such direction as to cut the intensity of the printing source to ment of the system, the output of the cell as am pli?ed by ampli?er I03 trips a relay composed of ' coil 63 and switch 59 to break the motor circuit. The exposure with the color light ‘as so adjusted (red for instance) is then made with this adjusted intensity and the procedure is repeated in suc cession for both green and blue light. Having brie?y ‘outlined the structure and op eration of that part of the color printer which is essential to an understanding of the present in vention, we will now describe how the present invention may be combined therewith to auto an inspection of Fig. 1, when the integrating photocell I6, is adjusting the red-printing inten sity for the negative, the compensating unit ad justs the ampli?er sensitivity according to the red sensitivity of the paper, and likewise for the printing with green and blue light. ' The compensator used in this‘ manner would be moderately useful, but it can be made of much more value if ‘the compensating chart I 29 is printed on the printer it is to control. This not only eliminates the need for the sensitometer, but introduces complete compensation for any acci matically compensate the printer control for dental variation in the behavior of the automatic changes in the sensitometric characteristics of a new paper-processing combination relative to the printer intensity controller. combination for which the printer is initially ad justed. According to the present invention we in corporate the physical densitometer, described above relative to determining the sensitometric the instrument shops. Suppose we have received a new printer from It is to be adjusted to make satisfactory prints on a paper of average characteristics. Since it contains the compensat ing unit above described, some set of re?ectors is characteristics of a new paper and processing 40 required for placement in the compensating unit to set the ampli?er sensitivities at an initial value. combination, in the printer control. It is shown in the box shown in dotted lines, labeled “com A stable uniform gray re?ector can be used, rather than a set of dye deposits. With this ‘gray pensator unit” at the left end of Fig. 1. It com prises a light source I25 of known intensity which re?ector in place, the printer is adjusted by trial can be successively intercepted by red, green and 45 until satisfactory prints result. Now suppose we have available a transparent blue ?lters Rc, Go and Be, respectively, carried color chart or negative I32 such as is shown in by disk I26 mounted on shaft I21. Also mounted on shaft I2‘I'is a turn-table I28 on which is po Fig. 2. The red, green and blue ?lters R, G, and sitioned a compensating chart I29 having cyan, B pass su?iciently narrow bands of the spectrum magenta and yellow dye deposit areas, C. M, and 60 that when they are combined with any one of the Y respectively, said chart being made by giving projection lens ?lters the transmitted light ex poses only one of the layers of the multi-layer the paper to be used a sensitometric exposure to printing paper. A cyan dye deposit will result red, green and blue light and processing the same from the image of the red ?lter, a magenta dye by the processing procedure to be used in con 65 deposit from the green ?lter and a yellow dye junction with prints made on the printer. deposit from the blue. Transmittancesof the ?l This chart is oriented with respect to the ?lter ter sectors of this chart must be so adjusted that disk I26 so that as the shaft I2‘! is indexed the when it is used as a negative to make a print on ' cyan area will be illuminated by red light, the the paper for which the printer has been ad magenta area will be illuminated by green light justed, this print can be used interchangeably and the yellow area by blue light. ' Or, stating it with the gray re?ector in the compensating unit. another way, each of the primary color lights will To make such adjustment easy, the color ?lter illuminate an area the color of which is a sub sectors should occupy a relatively small portion tractive primary thereof. Or, each area of the chart is illuminated by a light which is comple of the chart area; the rest should be a uniform mentary in color with respect thereto. The shaft 55 color and can conveniently be gray as indicated. The adjustment is then made by adding neutral 22 on which the ?lter disk I5 of the printer is mounted is positively connected to the shaft I21 density to the ?lter sectors. ' so that corresponding color ?lters are moved into A printed compensator chart can now be put the printing beam and the light beam of the com into the compensating unit and the printer is pensator unit at the same time. We have indi ready to make prints on the paper which pro cated this connection as a chain drive I30 for duced the compensator chart. This chart can purposes of simplicity. Light re?ected by the re stay in the printer as long as no change occurs spective chart areas C, vM and Y are picked up by in the color sensitvity of the printing paper used, a photo-emissive type light-sensitive cell I3I the processing balance, or printer behavior. The which will be referred to as the compensating cell. 7‘ gray ?lter and the compensator chart negative 8,500,” 7 I" should remain available. If any change of any of these factors occurs, the gray ?lter is placed in the compensating unit and a new print 8 Reiernngnowtomgs.4,5,and6thecom pensating unit of which the compemating cells Ba,Bo.andBsformapartwilinowbedescribed. or compensator chart is made with said negative Three tungsten-?lament lamps L are mounted in chart. The resulting new compensator chart is separate compartments of a housing I". These then placed in the compensating unit, and the color balance of the print automatically returns to the point to which the original trial adjust ment was made. Whatever changes the printer lamps are preferably low-wattage lamps with horizontal line ?laments. Each of the ?laments is imaged by a high-aperture, condenser-lens pair in on a slit Ill. The light forming the image control, the paper or the processing tries to make 10 is ?ltered by an appropriate color filter I" placed in the print balance will first take place on the between the slit and the condenser lens pair. print of the compensator chart, which will re The?lterinfrontofoneofthelampsisred and move the effect in the subsequent printing of the is designated Fa, another is green and designated picture negatives. The printing balance is, Fe, and the last is blue and designated Pa. The therefore, controlled solely by the characteristics slits are on the axis of a semi-cylindrical end I" of the compensator chart negative, and as long as on the housing and around which is wrapped the this is constant the printer will always return to compensator chart III’, of the form shown in making prints of the original color balance. Fig. 6, and into which are cut windows III to The present compensating unit is applicable disclose the colored areas of the compensator to the embodiment of the color printer shown in 20 chart. The slit is covered by a ?eld lens I“ the above-noted Tuttle and Brown copendlng ‘which images the condenser lens on the com application which uses barrier-type photocells pensator chart. The chart is held in wrapped for integrating purposes, as well as the embodi relation with the end of the housing by any suit ment using photo-emissive type cells as set forth able means such as a ?exible metal strap, not above, and such a modi?cation of the present 25 shown, which is also wrapped around the end of the housing in covering relation with the chart. invention will now be described. The arrangement and size of the colored areas In Fig. 3 we have shown the embodiment of the in the compensator chart conform to that of the color printer control shown in Fig. 7 of the above window dimensions and pattern in the semi-cylin noted Tuttle and Brown application modi?ed to drical end of the housing and is optional. This incorporate the cells of a compensating unit in chart is made exactly in the same manner as accordance with the present invention. A com the one described in connection with the ?rst plete description of this type of printer control can be had by referring to said Tuttle and Brown mentioned embodiment of the invention, and the application, but enough of it will be brie?y out negative of which this is a print comprises three lined here to make the application of our com color ?lters on a gray background, in an ar pensating unit thereto readily understandable. rangement which is, naturally, a proportional reduction of the print arrangement, the reduction being equal to the magni?cation factor of the printer. The color ?lters used in this negative This form of the printer control uses three sep arate integrating cells of the barrier-layer type, one Ca covered with a red ?lter, another Co cov ered with a green ?lter, and the third Ca cov ered with a blue ?lter. These cells measure the light transmitted by the color negative i4 and are individually cut into the measuring circuit by means of a cam 42 operating switches Sn, So and Se in the proper timed relation with the indexing of the ?lter sectors R, G and B into the printing beam. In this embodiment, a servo system is used to control the intensity of the printing source it. This involves connecting a standard source of potential in bucking relation to the output of the integrating cell to provide a null system, and feeding the output of the cell and standard potential through a servo-amplifier 32, the reversible motor Me of which drives the rheostat II to adjust the intensity of the printing are the same as the printer lens ?lters, plus neu tral densities in the required amounts. Each area of the compensator chart, then. is illuminated by a slit source which emits light of selected quality only in directions which con?ne the illumination to the desired chart area. and all of the light is directed to the chart areas in a radial plane. Since the surface of the com pensator chart is specular. all of the light re ?ected by the surface returns to the cylindrical axis and is largely lost. The light which is to activate the compensating cells is that which is diffusely re?ected by’ the print areas. Part of this light from each chart area falls on two of the barrier layer type compensating cells having the same color sensitivity so disposed as to safely lamp l0 until the output of the measuring cell is avoid the specular reflections, but to intercept as equal and opposite to that of the standard source much as possible of the diffused light. see Fig. 5. of vpotential connected in bucking relation thereto. The only change in this printer control which the present invention necessitates is the substitu Because of space limitations, the compensating cells Ba and Bo which are to be illuminated by light re?ected from the cyan and magenta areas of the chart are each so placed, not shown, as to receive light from both print areas. Confmion of response is eliminated, however, by covering tion of three barrier-layer type photo-cells Ba, Ba and Ba for the standard source of potential normally used to buck, or oppose, the output of measuring cells Ca, CG and Ci; of the printer. These photo cells Ba, Ba and Ba constitute a part of the compensating unit to be described and the compensating cell Ba is connected in opposition with the red integrating cell Ca and the com pensating cell B0 in opposition to the integrating cell Co and the compensating cell Ba in opposition to the integrating cell Ca. Each of the inte grating cells Ca, Co, and Cs and its corresponding one of compensating cells Ba, Bo and Ba are con nected in pairs and in bucking relation into the control circuit by rotation of the cam 42. TI half of each cell with an opaque sheet. so that light re?ected from the cyan print area acts onlyontheuncoveredhalfofonecelLandthe light from the magenta area acts only on the uncovered half of the other cell. The responses of these small cell-elements are adequate. The amount of energy re?ected by the yellow print area is so small. however, that two complete cells andalargerchartareaaremedtoimprovethe emciency of its interception. As will be appreciated, the compensating cell Baofthecompensatingunitwhichmeasuresthe 2,000,040 I light di?usely re?ected from the cyan area of the chart when illuminated by red light is connected in opposition to the integrating cell Ca of the printer which measures the intensity of the red 10 means for individually integrating and measuring the intensity of each of the three colors in the printing beam transmitted by the negative and adapted to give a signal when the intensity of each colored light is a pre-selected value; means for varying the intensity of each of the three light transmitted by the negative. Likewise the compensating cell Ba measuring the light re ilected by the magenta area when illuminated by green light is connected in opposition to the green filtered integrating cell Co, of the printer. And ?nally, the compensating cell Be is connected in opposite with the blue-sensitive integrating pensator unit connected to the photo-electric in tegrating and measuring means to modify the cell Ci; of the printer. sensitivity oi’ response thereof and' adapted to Where more than one colors in the printing beam and adapted to be controlled by the signal given by said photo-elec tric integrating and measuring means; of a com compensate for variations in the exposure re quirements of a negative introduced by changes re?ected from a single chart area they will be connected in parallel so that their output adds up 15 in the color sensitivity of the printing material as compared with the color sensitivity for which and is the equivalent to the output of a single cell the printing control is initially adjusted and having twice the sensitivity of one. changes in response of said photo-electric in A compensating unit of this type provides cor tegrating and measuring means of the printer. rect action for a color printer using barrier layer 2. In a color printer for making color prints on type integrating cells, provided a null-balancing 20 a color-sensitive printing material from a color system is used. That is, the response of the com negative, the combination with means for uni pensating cells and the response of the integrat formly illuminating said negative with a light ing cells must be equal and of opposite polarity source including the three primary colors; means when the printer is at printing ‘balance. In this application, instead of requiring that increased 25 for projecting an image of said negative onto a sheet of color-sensitive material; means for in compensator response decrease the integrator dividually integrating and measuring the intens sensitivity, an increase in compensator response ity of each of the primary colors in the printing directly requires an equal increase 01' integrator beam transmitted by said negative and adapted to response to return the printer control to balance. With the present compensator unit it is possible 30 give a signal when the intensity of each color reaches a pre-selected value; means for varying to readily adjust the printer action to accommo the intensity or each of the primary colors in the date abnormal color negatives merely by vary printing beam and adapted to be controlled by ing the intensity of the compensator light sources. the signal given by said integrating and measur For example, in Fig. 7 we‘have shown how the lights of the compensating unit may be wired so 85 ing means; of means for compensating for varia tions in the exposure requirements introduced by that each lamp L of the compensator unit can be changes in response of said means for integrating operated at any one of three intensity levels, the and measuring the intensity of the primary colors changes occurring simultaneously if a simple 'in said printing beam, due to a change in the change to in over-all print density is required, or independently, if changes in color balance are re 40 color sensitivity of the printing material and processing procedure for the exposed printing quired. The three lamps are connected in par material, and comprising a compensating chart allel to the secondary of a transformer T con which is a positive print made by said printer on nected to a 110 0 line. By turning a dial “2 a sample of the color printing material to be'used over a scale marked “over," "normal" and “un der" a di?erent amount of resistance can be cut 46 and exposed to light of the three primary colors, each having a given intensity and processed ac into the primary of the transformer T to simulta cording to the procedure to be used; means for neously change the intensity of each of the three illuminating this chart with a red, a green and compensating lamps for control of the over-all a blue light source of given intensity; means for density of the prints. On the other hand, each of the lamps have a group of different resistances 50 measuring the amount of light re?ected by said chart when illuminated by each of said primary in their own individual circuits which may be in color light sources; and means for connecting dividually cut into the circuits of the lamps by said integrating and measuring means with said turning the proper one of the dials Ill between last-mentioned measuring means whereby the re positions marked “over,” “normal” and "under” on the panel of the control to alter the color bal 55 sponse, and ultimately the signal, of the former is modified by and in accordance with the re ance of the prints made from abnormal negatives. sponse of the latter. Each lamp circuit will preferably include an ad 3. In a color printer for making a color print justable .resistance R for facilitating initial ad on a color-sensitive printing material from a color justment of the compensating unit. While we have shown and described certain 60 negative, the combination with means for uni compensating cell is used to measure the light speci?c embodiments of our invention we are aware that many modi?cations thereof are pos formly illuminating said negative with the light source including red, green and blue light; photo electric means for individually integrating and sible. Our invention, therefore, is not to be lim measuring the intensity of each of the three col ited to the precise details of construction shown and described but is intended to cover all modi 65 ors in the printing beam transmitted by said neg ative and adapted to give a signal when the in ?cations coming within the scope of the appended tensity of each color is a pre-selected value; claims. means for varying the intensity of each of the Having thus described our invention, what we three colors in the printing beam and adapted to claim is new and desire to protect by Letters Pat 70 be controlled by the signal given by said photo ent of the United States is: , electric integrating and measuring means; of a 1. In a color printer for making a color print compensator unit for compensating for variations on a colors-sensitive printing material from a in the exposure requirements introduced by color negative, the combination with means for changes in the color sensitivity of the printing illuminating ‘said negative with a light source in cluding red, green and blue light; photo-electric 76 material and by changes in the response of said 2,500,040 - 12 ll photo-electric integrating and measuring means; for variations in the exposure requirements or a negative introduced by changes in the color semi tivity of the printing material as compared with that for which the integrating and measuring means of the printer is initially adjusted; and comprising a compensating chart having separate cyan, magenta and yellow areas and produced by making a color print on the printing material to be used on the printer using given red, green and blue ?lters, respectively, as a negative and using known exposure conditions; means for il luminating each of said cyan, magenta and yel and comprising a color-compensating chart made on the above printer by exposing a sheet of the printing material to a negative including sepa rate red, green and blue ?lter areas of known transmission characteristics, whereby said chart includes three separate cyan, magenta and yel low dye areas; means for illuminating each of said chart areas with a light source of known intensity and of a color substantially comple mentary to that of the area; a photo-cell for measuring the amount of light reflected from each of said chart areas, and means for connect low areas of said chart with a beam of known in ing said photo-cell into the circuit of said photo tensity and of a color substantially complemen tary thereto; a compensating light-sensitive cell for measuring the amount oi’ light reflected by each of said chart areas when so illuminated: electric integrating and measuring means of the printer so that the sensitivity of response of the latter is modi?ed in accordance with and by the output of the former. and means for connecting said compensating 4. In a color printer for making a color print light~sensitive cell in circuit with said photo on a color-sensitive printing material from a 20 electric cell so that the output of the latter is color negative, the combination with means for modi?ed in accordance with the output of the uniformly illuminating said negative with a light source including red, green and blue light; photo electric means for individually integrating and measuring the intensity of each of the three colors of the printing beam transmitted by said negative and adapted to give a signal when the intensity former. 6. A color printer according to claim 5 in which a single photo-electric cell of the photo-emissive type is disposed in the printing beam to integrate and measure the intensity thereof, and an am pli?er is connected in circuit therewith to ampli of each color is a pre-selected value; means for varying the intensity of each of the three colors in the printing beam and adapted to be controlled ; by the signal given by said photorelectric inte grating and measuring means; of a compensator unit for compensating for variations in the ex iy the output thereof; means for successively in dexing red, green and blue ?lters into the print ing beam in front of said cell to spectrally select the light striking said cell; and said compensator includes a "white" illuminating beam; means for successively moving the di?erent color areas of posure requirements introduced by changes in said chart into said illuminating beam; means for the color sensitivity of the printing material, and I ~ successively moving red, green and blue ?lters comprising a compensator chart bearing three into said illuminating beam in front of said chart. color areas each being a different one of the subtractive primary colors; means for illuminat said two last-mentioned means synchronised so that each color area of the chart is illuminated ing each of said areas of said chart with a source by a color substantially complementary thereto; of known intensity which is complementary in 1 - means for synchronizing said two sets of color color to the area; means for individually inte~ filters so that at any time a ?lter of the same color grating and measuring the intensity of light dif isinterposedintheprintingbeamandsaidil fusely reflected by each of said areas; and means luminating beam; and means for connecting said compensating cell into the ampli?er circuit so for connecting the means for integrating and measuring the intensity of the primary colors in the printing beam and the means for integrating and measuring the intensity of the light diffusely re?ected by each of said color areas together so that the response of said ?rst integrating and measuring means and measuring light of one of the primary colors is modi?ed in accordance with the response of the second-mentioned integrat ing and measuring means when measuring the that it acts as a load resistor for said ampli?er. 7. Acolorprinteraccordingtoclaimbandin eluding means for varying the intensity of the illuminating means for said chart areas to ad Just the over-all density and to alter the color 50 balance oi a print made on the printer. . 8. The color printer according to claim 5 and in which separate sources are provided for il luminating each of said chart areas; and includ amount of light re?ected by a color area the color ing means for simultaneously adjusting the in of which is complementary to that of said pri 55 tensity of each of said sources by the same mary color. > . amount to obtain a change in over-all density 5. In a color printer for making a color print of a print made on the printer.‘ on a color-sensitive printing material from a color 9. A color printer according to claim 5 and in negative, the combination with means for illumi-. which separate sources are provided for illum nating said negative with a light source including 00 inating each of said chart areas; and including red, green and blue light; means for individually means for individually adjusting the intensity varying the intensity of each of the red, green of each of said sources to obtain a change in and blue lights in the printing beam transmitted color balance in a print made on the printer. by the negative; means including a photo-electric 10. A color printer according to claim 5 in cell disposed in the printing beam for individu which three photo-voltaic type photo-cells, one ally integrating and measuring the intensity of sensitive to red light, one sensitive to green light. each color light in the printing beam and adapted and a third sensitive to blue light, are disposed to give a signal for stopping said intensity vary in the printing beam to integrate and measure ing means when the intensity of each color light the intensity thereof; means for selectively con in the printing beam reaches a pre~selected value, 70 necting each of said cells in circuit with said the response of said integrating and measuring integrating and intensity measuring means; and means being initially adjusted in accordance with said compensator includes means for illuminat a printing material having a given color sensitiv ity: of a compensating unit connected to said in ing each of said color areas of the chart with a tegrating and measuring means to compemate tially complementary thereto; a photo-voitaic light of known intensity and of a color substan 8,500,049 13 i compensating cell disposed to scan the cyan area of the chart, a second photo-voltaic type com pensating cell disposed to scan the magenta . . 14 . 13, in which the illuminating means for each chart area includes ‘an illuminated slit substan tially coinciding with the axis of said semi-cyr area of the chart, and a third sensitive photo voltaic compensating cell disposed to scan the yellow area of said chart; the compensating cell lindrical end of the housing, and wherein each ' integrating cell and the compensating cell scan ning the yellow area connected in opposition with each chart area for controlling the over-all den photo-electric cell is disposed adjacent to said slit and outside of the cone of light passing be scanning the cyan area connected in opposition, tween said slit and the chart area. with the red sensitive integrating cell,'the com 15. A compensating unit according to claim pensating cell scanning the magenta area con 13, including means for simultaneously adjust nected in opposition with the green sensitive 10 ing the intensity of the illuminating means for sity of the color print and for individually adjust the blue-sensitive cell so that each pair of cells ing the intensity of the illuminating means for is adapted to be selectively connected in circuit the different chart areas for controlling the color with said integrating and intensity measuring 16 balance of the print. means of the printer. -> . 16. A compensating unit according to ‘claim 13, in which the illuminating means for each of‘ the respective chart areas comprises a sep the negative-integrator type and for indicating arate lamp; a circuit for connecting each of said any adjustment required‘ in the response of the three lamps to a common source of potential; photoelectric integrating and measuring means 20 9. variable resistance in series with each separate 11. A compensating unit of the type described for use in combination with a color printer of ' thereof which might be required because oi’ a change in the color sensitivity of a given print ing material to be used, comprising a color com pensating chart having threeseparate areas each of a different‘ color which is a positive print made with said printer on a sample of the color print ing material to be used in the printer and expomd to light of the three primary colors of given in lamp for varying the intensity of the lamps indi vidually for control of color balance in a color print; and a variable resistance in the circuit 25 common to all of the lamps for control or over all density of a color print. 17. A compensating unit of the type described for use in combination with a'color printer oi’ the negative-integrator type and for indicating tensity and processed according to the proce 30 any adjustmentrequired in the response of the dure to be used; means for illuminating each of photoelectric integrating and measuring means said chart areas with a light beam of known thereof which might be required because of a intensity and of a color substantially comple change in the color sensitivity of a given printing mentary to that of the area, and a separate material to be used, comprising a color com light~sensitive cell for scanning each of said 35 pensating chart having three separate areas of illuminated chart areas to measure the amount a different color which is a positiveprint made of light re?ected thereby, the output of each with said printer on a sample of the color print oi’ said light-sensitive cells indicating any change ing material to be used in the printer and exposed in response which might be required in the to light of the three primary colors of given in printer control to compensate for changes in the ii tensity and processed according to the procedure actual or apparent color sensitivity of the print ing material to be used in the printer. 12. A compensating unit according to claim 11, and in which said light-sensitive cells are so disposed relative to the chart areas they re spectively scan and the chart areas are so illum inated that only the light di?‘usely re?ected by said areas reaches said cells and is measured thereby. to be used; means for projecting a beam of “white” light of known intensity onto said chart; means for successively indexing the different areas of said chart into said beam; a tri-color 45 ?lter including separate ?lters each of a color substantially complementary to one of the three areas; means for successively indexing said ?lters to bring di?erent ?lters into said illuminating beam, said last-mentioned means synchronized 13. A compensating unit of the type described with said chart indexing means so that each comprising a housing having a semi-circular end 50 chart area is illuminated by light complementary wall provided with three spaced windows; a com to itself in color; and a light-sensitive cell for pensating chart having three separate areas, measuring the amount of light reflected by each each of a different color, wrapped around the oi’ said chart areas when so illuminated. semi-circular end of said housing with a differ ent one oi’ each of said colored areas framed by 55 FRANKLIN C. WILLIAMS. each of said windows and facing the axis of said FORDYCE M. BROWN. semi-circular end; separate means in said hous ing for uniformly illuminating each of the chart areas with light rays directed radially to the chart area and of known intensity and being a color substantially complementary to that of the chart area illuminated thereby; and a plurality of photo-electric cells in said housing, each ar ranged to scan a different chart area, said cells disposed relative to the chart areas and the light rays illuminating the same so that they are not a?ected by light specularly re?ected by said areas but only by light di?'usely re?ected by said chart areas. , nmnncas orran The following references are of record in the ?le of this patent: . . UNITED STATES PATENTS Number 2,169,009 2,244,992 2,289,161 2,319,898 2,384,280 2,388,842 14.A compensating unitaccordingtoclaim 10 2,402,880 Name I Date Seymour ......... _. Aug. 8, Guerrero ________ -_ June 10, Morse ..__-_-'_ _____ -_- Jan. 8, Zurian __-_‘ ______ __ May 25, Goldsmith ______ _- Sept. 4, Hanson .........-- Nov. 13, O'Grady __. ____ _- June as, 1939 1941 1942 1943' 1948 1949 me Certi?cate of Correction Patent No. 2,500,049 March 7, 1950 FRANKLIN O. WILLIAMS ET AL. It is hereby certi?ed that errors appear in the printed speci?cation of the above numbered patent requiring correction as follows: Column 9, line 11, for the word “opposite” read opposition; column 14, line 46, after “three” insert chart; and‘ that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent O?ice. Signed and sealed this 27th day of June, A. D. 1950. [am] THOMAS F. MURPHY, Assistant C'ommz'ssz'oner of Patents. Certi?cate of Correction Patent No. 2,500,049 March 7, 1950 FRANKLIN C. WILLIAMS ET AL7 It is hereby certi?ed that errors ‘appear in the printed speci?cation of the above‘ ’ numbered patent requiring correction as follows: Column 9, line 11, for the word “opposite” read opposition; column 14, line 46, after "three.” insert chart; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent O?ice. Signed and sealed this 27th day of June, A. D. 1950. [BM] THOMAS F. MURPHY, Assistant Oommz'ssz'aner of Patents. Certi?cate of Correction Patent No. 2,500,049 March 7, 1950 FRANKLIN O. WILLIAMS ET ALf It is hereby certi?ed that errors appear in the printed speci?cation of the above numbered patent requiring correction as follows: Column 9, line 11, for the word “opposite” read opposition; column 14, line 46, after “three” insert chart; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Of?ce. Signed and sealed this 27th day of June, A. D. 1950. [am] THOMAS F. MURPHY, Assistant Commissioner of Patents.