U.S. patent number 3,929,487 [Application Number 05/095,901] was granted by the patent office on 1975-12-30 for spectral balancing means for color photography.
Invention is credited to Harbans Singh.
United States Patent |
3,929,487 |
Singh |
December 30, 1975 |
Spectral balancing means for color photography
Abstract
A photographic material comprising a spectral balancing means
for color photography consisting essentially of a layer of magenta
dye and yellow dye.
Inventors: |
Singh; Harbans (Odessa,
FL) |
Family
ID: |
26790736 |
Appl.
No.: |
05/095,901 |
Filed: |
December 7, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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583789 |
Oct 3, 1966 |
3588215 |
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Current U.S.
Class: |
430/510; 430/507;
359/885 |
Current CPC
Class: |
F21V
9/30 (20180201); G02B 5/223 (20130101); G03C
7/00 (20130101); F21Y 2103/00 (20130101) |
Current International
Class: |
F21V
9/00 (20060101); F21V 9/16 (20060101); G02B
5/22 (20060101); G03C 7/00 (20060101); G03C
001/84 () |
Field of
Search: |
;96/84,82,87R |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Kirk-Othmer Encyclopedia of Chemical Technology, 2nd Edition, Vol.
5, pp. 838 and 839 and Vol. 9, pp. 254 to 258 (1965)..
|
Primary Examiner: Smith; Ronald H.
Attorney, Agent or Firm: Buell, Blenko, and Ziesenheim
Parent Case Text
This is a division of application Ser. No. 583,789, filed Oct. 3,
1966, now U.S. Pat. No. 3,588,215.
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 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.
Description
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. I 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. I
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 the peaks at .+-. 3650 angstroms,
.+-. 4050 angstroms and .+-. 4360 angstroms and substantially
absorbs the .+-. 3130 angstroms peak characteristic of all white
fluorescent light sources (cool 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. Preferably, dyes are combined
to get an absorbance curve similar to curves hereafter described.
Preferably, I use gelatin as the carrier although any other
suitable optical transmission carrier may be used to carry the
dyes.
In the foregoing general statement of my invention, I have set out
certain objects, purposes and advantages of my invention. Other
objects, purposes and advantages will be apparent from the
following description and the accompanying drawings in which,
FIG. 1 is a curve of absorbance characteristics of one of the dyes
combined according to my invention;
FIG. 2 is a curve of absorbance characteristics of a second dye to
be combined with the dye of FIG. 1 to produce a spectral balancing
means according to my invention;
FIG. 3 is a curve of absorbance of spectral emission in a preferred
embodiment of my invention;
FIG. 4 is a curve of absorbance of spectral emission in a second
embodiment of my invention;
FIG. 5 is a curve of absorbance of spectral emission in a third
embodiment of my invention;
FIG. 6 is a spectral response curve of an ortho-chromatic film
exposed to the spectral emission of a typical cool-white
fluorescent light source without balancing its spectral
emission;
FIG. 7 is a spectral response curve of an ortho-chromatic film
exposed to the spectral emission of a typical cool-white
fluorescent light source using the embodiment of my invention of
FIG. 3;
FIG. 8 is a curve as in FIG. 7 using the embodiment of my invention
of FIG. 4;
FIG. 9 is a curve as in FIG. 7 using the embodiment of my invention
of FIG. 5;
FIG. 10 is a spectral response curve of an ortho-chromatic film
exposed to the spectral emission of a typical warm-white
fluroescent light source without balancing its spectral
emission;
FIG. 11 is a curve as in FIG. 10 using the embodiment of my
invention which was also used in FIG. 3;
FIG. 12 is a curve as in FIG. 10 using the embodiment of my
invention which was used in FIG. 4; and
FIG. 13 is a curve as in FIG. 10 using the embodiment of my
invention which was also used in FIG. 5.
Referring to the drawings, I have illustrated in FIG. 1 an
absorbance curve of one preferred dye component for combining to
form the balancing means of my invention and in FIG. 2 an
absorbance curve of a second preferred dye component for combining
with the dye of FIG. 1 to form the balancing means of my
invention.
In order to illustrate the effectiveness of the spectral balancing
means, I prepared three gelatin carriers with dye combinations
which would effectively balance the spectral emission of
fluorescent sources. The absorbance curve values of each device
were determined using a spectrophotometer and appear in Table I
below.
Table I ______________________________________ Spectral Absorbance*
Wavelengths in Embodiment Embodiment Embodiment Angstroms No. 1 No.
2 No. 3 ______________________________________ 3000 1.46 0.55 1.50
3100 1.35 0.40 1.50 3200 0.90 0.35 1.30 3300 0.60 0.30 0.83 3400
0.65 0.27 0.90 3500 0.70 0.24 0.95 3600 0.70 0.22 1.00 3700 0.64
0.23 0.94 3800 0.55 0.25 0.85 3900 0.56 0.27 0.90 4000 0.62 0.30
1.00 4100 0.66 0.34 1.05 4200 0.68 0.36 1.06 4300 0.64 0.37 1.02
4400 0.58 0.35 0.95 4500 0.50 0.32 0.83 4600 0.44 0.28 0.72 4700
0.38 0.24 0.62 4800 0.34 0.20 0.54 4900 0.33 0.19 0.48 5000 0.34
0.19 0.47 5100 0.38 0.20 0.49 5200 0.40 0.22 0.51 5300 0.42 0.22
0.50 5400 0.42 0.20 0.50 5500 0.40 0.18 0.48 5600 0.38 0.18 0.44
5700 0.30 0.16 0.35 5800 0.19 0.10 0.22 5900 0.10 0.05 0.12 6000
0.07 0.02 0.04 6100 0.02 0.01 0.00 6200 0.00 0.00 0.00
______________________________________ *At any given wavelength,
the spectral absorbance value relates the amoun 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. 1 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 filters for color photograph become opaque
below .+-. 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 invention on the response of
photographic emulsions and materials to spectral emission from
fluorescent sources I had spectrographic negatives prepared
exposing photographic material to fluorescent sources through a
spectral balancing 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 determine 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 following Table II and
Table III and spectral response curves were plotted, which are
FIGS. 6 through 13.
Table II
__________________________________________________________________________
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 Angstroms Effects of No. 1 No. 2 No. 3 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 Base* 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 .42 .14 .28 .14 4500 .42 .14 .42 .14 4600 .42 .28 .42
.14 4700 .56 .28 .56 .28 4800 .56 .42 .56 .42 4900 .56 .42 .56 .42
5000 .70 .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 5500
.56 .42 .56 .42 5600 .42 .14 .28 Base* 5700 .28 .07 .20 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. **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 THE SPECTRAL
EMISSION OF A WARM WHITE FLUORESCENT LIGHT SOURCE Wavelengths
Without Balanced by Balanced by Balanced in Balancing Embodiment
Embodiment by Embodi- Angstroms Effects of No. 1 No. 2 ment 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 .14 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. **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.
The devices used in the foregoing tests were made of gelatin
containing the following dye transfer (imbibition) dyes:
Embodiment No. 1 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
films 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 had excellent color balance.
It will be apparent from the foregoing tables and curves that my
invention has a very selective absorption characteristic for peak
emissions of fluorescent light sources and at the same time changes
the relative transmission of wavelengths in the band .+-. 3000
angstroms to .+-. 6300 angstroms. Accordingly, broadly stated, my
invention has a selective absorption for peak emissions of
fluorescent light sources and adjusts the relative transmission of
wavelengths in the band .+-. 3000 A to .+-. 6300 A. Preferably, the
spectral balancing device of my invention has a spectral absorbance
curve lying between the curves of FIG. 4 and FIG. 5 and
particularly similar to that of FIG. 3.
The spectral balancing means of my invention may be applied to a
fluorescent source envelope or to a separate carrier member as
described herein, or it may be applied directly to the photographic
film base and 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.
* * * * *