US3929487A

US3929487A - Spectral balancing means for color photography

Info

Publication number: US3929487A
Application number: US095901A
Authority: US
Inventors: Harbans Singh
Original assignee: Individual
Current assignee: Individual
Priority date: 1966-10-03
Filing date: 1970-12-07
Publication date: 1975-12-30
Anticipated expiration: 1992-12-30

Abstract

A photographic material comprising a spectral balancing means for color photography consisting essentially of a layer of magenta dye and yellow dye.

Description

United States Patent m Singh Dec. 30, 1975 1 SPECTRAL BALANCING MEANS FOR COLOR PHOTOGRAPHY Related US. Application Data [62] Division of Ser. No. 583,789, Oct. 3, 1966, Pat. No.

[52] US. Cl. 96/84 R; 96/2; 96/87 R [Sl] Int. Cl. 603C 1/84 [58] Field of Search 96/84, 82, 87 R [56] References Cited UNlTED STATES PATENTS 2,219,304 10/1940 Gaspar 96/84 R 2,219,305 10/1940 Gaspar 96/84 R 2,219,306 10/1940 Gaspar 96/84 R 3,234,023 2/ 1966 De Remaix 96/84 R OTHER PUBLICATIONS Kirk-Othmer Encyclopedia of Chemical Technology 2nd Edition, Vol. 5, pp. 838 and 839 and Vol. 9, pp 254 to 258 (1965).

Primary Examiner-Ronald H. Smith Attorney, Agent, or Firm-Buell, Blenko, and Ziesenheim [57] ABSTRACT A photographic material comprising a spectral balanc ing means for color photography consisting essential]: of a layer of magenta dye and yellow dye.

2 Claims, 13 Drawing Figures US. Patent D6C.30, 1975 Slleet 1 of5 3,929,487

Absorbonca Wavelength (Millimicrons) Absorbonce co 0 tbi'o b Wavelength (Millimicrons) Absorbonce a In N 30 Wavelength (Millimicrons) U.S. Patent Dec. 30, 1975 Spectral Response Spectral Response Sheet 3 of5 V 3,929,487

Wavelength (Millimicrons) F! g a 8 I Wavelength (Millimicrons) mew? l 'mms S PEC'IRAL BALANCING MEANS FOR COLOR PHOTOGRAPHY This is a division of application Ser. No. 583,789, filed Oct. 3, I966, now US. Pat. No. 3,588,215.

This invention relates to spectral balancing means and methods of spectral balancing and particularly to spectral balancing means for use in order to properly balance the spectral emission of carbon arc and mercury discharge spectral energy sources.

I shall particularly describe the invention in connection with a typical mercury discharge spectral energy source, fluorescent lighting. Fluorescent lighting is very much used for illumination in offices, public buildings and homes. It has many advantages for general illumination, being soft and very efficient. However, it is well known that fluorescent lighting is unbalanced in its spectral emission characteristics and cannot be satisfactorily used for many purposes where a balanced spectrum is required. Many attempts have been made in the past to find a satisfactory method for balancing the spectral emission of fluorescent sources or to correct the inherent difficulties by modifying the spectral distribution characteristics of fluorescent sources, but without success. l have invented a means and method of spectrally balancing fluorescent sources which may be used wherever a balanced fluorescent source is desired.

I shall particularly describe the invention in connection with photography using color film. It is well known that fluorescent lighting cannot be used satisfactorily for color photography. Consequently, when television or motion picture cameras are being used for color reproduction under artificial light, special lighting sources must be used. If the objects to be photographed are also illuminated by fluorescent artificial light sources, the special lighting sources must overpower them; if such special lighting sources are not permanently installed at the area, they must be carried there and installed and used. This is expensive and inconvenient, but is necessary because no satisfactory method for balancing the spectral emission of fluorescent sources has been found prior to the present invention.

I have discovered a means and a method of balancing the spectral emission of fluorescent sources which makes it possible to use conventional fluorescent light sources for color reproduction. l have successfully produced photographic results under fluorescent lighting which are completely free from the washed out appearance characteristic of color reproduction by fluorescent lighting in the past and which are comparable to color reproduction by daylight illumination.

In a preferred embodiment of my invention, I provide a spectral balancing means absorbing ultra violet radiation without distortion of violet and deep blues and with a relative strengthening of blue green and green wavelengths of light. A device of my invention preferably selectively reduces i re peaks at i 3650 angstroms, i 4050 angstroms and I 4360 angstroms and substantially absorbs the :t 3130 angstroms peak characteristic of all white fluorescent light sources (cooi and warm whites) presently in use. The device of my invention is preferably prepared by combining known color filter materials to produce the peculiar advantages here set out. Preferably, I combine dyes on a suitable carrier to selectively reduce the emission peaks which are characteristic of all white fluorescent light sources. Prefera bly, dyes are combined to get an absorbance cur similar to "irves hereafter described. Preferably, I u gelatin as the carrier although any other suitable op cal transmission carrier may be used to carry the dyt In the foregoing general statement of my invention have set out certain objects, purposes and advantag of my invention. Other objects, purposes and adva tages will be apparent from the following descriptii and the accompanying drawings in which, m FIG. 1 is a curve of absorbance characteristics of o: of the dyes combined according to my invention;

FIG. 2 is a cur e of absorbance characteristics of second dye to be combined with the dye of FIG. I

produce a spectral balancing means according to n 5 invention;

FIG. 3 is a curve of absorbance of spectral emissii in a preferred embodiment of my invention;

FIG. 4 is a curve of absorbance of spectral emissit in a second embodiment of my invention; FIG. 5 is a curve of absorbance of spectral emissit in a third embodiment of my invention;

FIG. 6 is a spectral response curve of an orth chromatic film exposed to the spectral emission 'of typical cool-white fluorescent light source without b: ancing its spectral emission;

FIG. 7 is a spectral response curve of an orth chromatic film exposed to the spectral emission of typical cool-white fluorescent light source using t'. embodiment of my invention of FIG. 3;

FIG. 8 is a curve as in FIG. 7 using the embodime of my invention of FIG. 4;

FIG. 9 is a curve as in FIG. 7 using the embodime of my invention of FIG. 5;

FIG. 10 is a spectral response curve of an orth chromatic film exposed to the spectral emission of typical warm-white fluroescent light source vritho balancing its spectral emission;

FIG. 11 is a curve as in FIG. 10 using the embot ment of my invention which was also used in FIG. 3

FIG. 12 is a curve as in FIG. 10 using the CI'IIbOt ment of my invention which was used in FIG. 4; an

FIG. 13 is a curve as in FIG. 10 using the embo ment of my invention which was also used in Fl". 5

Referring to the drawings, l have illustrated in FIG an absorbance curve of one preferred dye compone for combining to form the balancing means of my vention and in FIG. 2 an absorbance curve of a seco preferred dye component for combining with the dye FIG. 1 to form the balancing means of my inventioi In order to illustrate the effectiveness of the spect balancing means, I prepared three gelatin carriers w dye combinations which would effectively balance 1 spectral emission of fluorescent sources. The absl bance curve values of each device were determin using a spectrophotometer and appear in Table l l low.

Table I Spectral Absorbance' 6Q Wavelengths in Emlgodirpent Embodiment Embodim Table I-contmued Spectral Absorbance' Wavelengths in Embodiment Embodiment Embodiment Angstroms No 1 No. No.3

At any given wavelength. the spectral absorbance value relates the amount of spectral energy (of that specific wavelength) entering the spectral balancing means to the amount of spectral energy transmitted.

The absorbance curve of Embodiment No. I is plotted in FIG. 3, that of Embodiment No. 2 in FIG. 4 and that of Embodiment No. 3 in FIG. 5. Known color balancing falters for color photograph become opaque below :t 4000 A. To the contrary absorbance curves of my invention disclose transmittance of spectral energy in the near ultraviolet range.

To illustrate the effect of my inventio on the response of photographic emulsions and mat 'ials to 4 spectral emission from fluorescent sources I had spectrographic negatives prepared exposing photographic material to fluorescent sources through a spectral baiancing means of my invention and with none at all. Orthochromatic film was used rather than panchromatic film because the described spectral balancing means exhibit little transmission difference above approximately 5800 angstroms.

When the orthochromatic film was exposed to the fluorescent source, a step-density wedge of fine-grain silver was interposed. Each step of the wedge had an incremental density of 0.14. Thus, for example, two increments totaled 0.28, which for practical purposes represents a 2X difference in transmission or, in other terms, a one f-stop difference in lens aperture. These density increments are directly equivalent to absorption values of 0.14, 0.28, etc.

After the orthochromatic film was exposed, it was developed in a high-contrast, catalytic, paraformaldehydehydroquinone developer to a gamma above 3.0 and a toe" density less than 0.30. Low-contrast continuous tone spectrographic negatives were also produced, in order to verify the results of this high-contrast procedure.

To detennine the spectral response curves of the orthochromatic film, positive prints were made from the spectrographic negatives onto high gamma paper and developed to high contrast. The printing exposures were timed to print maximum possible density for all densities in the original negatives of 0.40 or less. The resulting positive prints thus show directly a contour of the photographic response from all wavelengths between 3000 and 5800 angstroms. From the prints data were tabulated into the foiiowing Table I1 and Table 111 and spectral response curves were plotted, which are FIGS. 6 through 13.

Table I1 SPECTRAL RESPONSE OF AN ORTHOCHROMATIC FILM TO THE SPECTRAL EMISSION OF A COOL WHITE FLUORESCENT LIGHT SOURCE Wavelengths Without Balanced by Balanced by Balanced by in Balancing Embodiment Embodiment Embodiment Angstrom! Effects of No. 1 No. 2 No. 3 I My Invention 3000 .42 .14 .28 Base 3100 .42 .14 .28 Base 3130 .84 .14 .56 Base 3200 42 .14 28 Base 3300 42 .14 .28 Base 3400 42 .14 28 Base 3500 42 .14 28 Ban 3600 .42 .14 .28 Base 3650 .98 .56 .84 .42 3700 42 .14 28 14 3800 42 .14 42 14 3900 42 .28 42 14 4000 .46 .28 .42 .14 4050" 1.12 .70 .84 .42 4100 .56 .28 42 14 4200 42 .28 42 14 4300 .42 .14 .28 .14 4360" 84 .56 .70 .42 4400 12 .14 .28 14 4500 42 .14 .42 14 4600 42 .28 .42 14 4700 56 .28 .56 28 4800 $6 42 .56 42 4900 56 42 .56 42 5000 .42 .56 42 5100 70 .42 .56 42 5200 70 .42 .70 42 5300 70 .56 .70 .56 5400 .78 .56 .70 .56 5460" 1.12 .84 1.12 .98- $500 56 .42 i .56 .42 7 5600 42 .14 .28 Base ate and -51 Table lI-continued SPECTRAL RESPONSE OF AN ORTHOCHROMATIC FILM TO THE SPECTRAL EMISSION OF A COOL WHITE FLUORESCENT LIGHT SOURCE Balanced by Balanced by Balanced by The printing exposures for making positive prints were timed to print maximum possible density for all densities in the original negatives of 0.40 or less.

"This wavelength designates an average of those wavelengths which comprise this "peak", which is characteristic of the spectral emission of a typical fluorescent light source.

Table III SPECTRAL RESPONSE OF AN ORTHOCHROMATIC FILM TO Tl'kF SPECTRAL EMISSION OF A WARM FLUORESCENT LIGHT SOURCE Wavelengths Without Balanced by Balanced by Balanced in Balancing Embodiment Embodiment by Embodi- Angstroms Effects of No. 1 No. 2 meat No. 3

My Invention 3000 .42 .14 .28 Base 3100 .42 .14 .28 Base 3130" .84 .20 .70 .14 3200 .42 .14 .28 Base 3300 .42 .14 .28 Base 3400 .56 .14 .28 Base 3500 .42 .14 .28 Base 3600 .42 .14 .35 Base 3650" .98 .56 .84 .42

. 3700 .42 .14 .42 .l4 3800 .56 .14 .42 .14 3900 .56 .14 .42 .14 4000 .56 .14 .56 .14 4050" .98 .56 .84 .42 4100 .56 .14 .56 .14 4200 .56 .14 .42 .14 4300- .56 .14 .42 .07 4360" .84 .42 .70 .28 4400 .42 .14 .42 Base 4500 .56 .14 .42 .14 4600 .56 .42 .42 .14 4700 .70 .42 .56 .28 4800 .70 .56 .56 .42 4900 .70 .56 .70 .42 5000 .70 .56 .70 .42 5100 .70 .56 .70 .42 5200 .70 .56 .70 .42 5300 .84 .56 .70 .42 5400, .70 .56 .70 .42 5460" 1.12 .70 1.12 .70 5500 .56 .42 .56 .28 5600 .42 .14 .42 .14 5700 .42 Base .28 Base The printing exposures for making positive prints were timed to print maximum possible density for all densities in the original negatives of 0.40 or less.

The devices used in the foregoing tests were made of gelatin containing the following dye transfer (imbibition) dyes:

Embodiment No. i 5 parts ASA magenta 5 parts ASA yellow Embodiment No. 2 2 parts ASA magenta 5 parts ASA yellow Embodiment No. 3 9 parts ASA magenta+ 12 parts ASA yellow.

In order to compare the results of using the foregoing Embodiments Nos. 1, 2, and 3 and the results of using the filters and combinations of filters presently known and the results of not using any of them, color motion pictures for television transmission and for conventional projection were produced under both cool white and warm white fluorescent light sources. All the flms exposed without use of my invention revealed the color imbalance characteristic of color film exposed to the spectral emission of fluorescent light sources. On the other hand, the films exposed using my inventions l excellent color balance.

It will be apparent from the foregoing tables 2 curves that my invention has a very selective abso tion characteristic for peak emissions of fluoresc light sources and at the same time changes the relat transmission of wavelengths in the band i 3000 a stroms to i 6300 angstroms. Accordingly, broa stated, my invention has a selective absorption for pt emissions of fluorescent light sources and adjusts relative transmission of wavelengths in the band i 3( A to i 6300 A. Preferably, the spectral balancing vice of my invention has a spectral absorbance cu lying between the curves of FIG. 4 and FIG. 5 t particularly similar to that of FIG. 3.

The spectral balancing means of my invention it be applied to a fluorescent source envelope or ti separate carrier member as described herein, or it n be applied directly to the photographic film base 2 Imp am, 1.

7 emulsion or material or as a modification of the fluorescent source phosphors.

While I have set out certain preferred embodiments and practices of my invention in the foregoing specification, it will be understood that this invention may be otherwise broadly practiced within the scope of the following claims.

I claim:

1. A spectral balancing means for color photography under a fluorescent light source consisting essentially of in combination in a single transfer dye layer a masion and a photographic material.

I i t

Claims

1. A SPECTRAL BALANCING MEANS FOR COLOR PHOTOGRAPHY UNDER A FLUORESCENT LIGHT SOURCE CONSISTING ESSENTIALLY OF IN COMBINATION IN A SINGLE TRANSFER DYE LAYER A MAGENTA DYE AND A YELLOW DYE IN THE RATIO OF 1:1 TO 2:5 COATED AND APPLIED AS ONE OF A SINGLE LAYER AND A PELLICLE ONTO ONE OF A PHOTOGRAPHIC FILM BASE, A PHOTOGRAPHIC EMULSION AND A PHOTOGRAPHIC MATERIAL

2. A spectral balancing means for color photography under a fluorescent light source consisting essentially of in combination in a single layer a magenta dye and a yellow dye in the ratio of 1:1 to 2:5 incorporated into one of a photographic film base, a photographic emulsion and a photographic material.