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Патент USA US2022978

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Dec. 3, 1935»
K. RÄNTscH
2,022,978
OBJECTIVES FOR TAKING, PRINTING AND PROJECTING LENTICULAR
FILMS
Filed June 15, 1934
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Patented Dec. 3, 1935
2,022,978
UNITED sTATEs ' PATENT OFFICE
2,022,973
OBJECTIVES FOR TAKING, PRÍNTING, AND
PROJECTING LENTICULAR FILMS
‘
Kurt Räntsch, Teltow-Seehof, near Berlin, Ger
many, assigner to Opticolor, Aktiengesellschaft,
Glarus, Switzerland.. a corporation of Switzer
land
Application June 15, 1934, Serial No. 730,715
In Germany June 22, 1933
7 Claims. (Cl. 95-2)
The invention relates to objectives for taking,
area in such a manner, that color falsiiications
printing and projecting lenticular iilms and more
yparticularly to such objectives which are associ
do not arise. Other shapes of diaphragms, for
ated with a multicolor screen or are provided
the rectangular diaphragm.
with a diaphragm which to a certain degree has
the eii’ect of a polychromatic screen.
instance a hexagon, may be applied instead of
It is a condition which is to be observed with 5
objectives the diaphragm of which is separated
,
If the image of the multicolor screen or'of
the diaphragm seen from the ñlm appears dis
torted, color dominants will be caused. The dis
tortion is especially great with such di-aphragms
or screens which are mounted in the interior of
the objective, this beingv corrected as a whole,
its single parts having no or an insufficient cor
from the ñlter, that the bands of the same color
shall have the same width, eventually inclusive
of opaque intervening spaces. In this case the
color iilter is often mounted in front of the ob- 10
jective, for instance in the front focal plane,
the diaphragm being mounted in the interior of
the objective.
'
'
jective, the bands of the screen are seen in an
For a fuller explanation of the invention, its
objects and advantages reference will be made l5
to the accompanying drawing wherein the same
reference characters denote the same parts
other greatness from the middle of the picture
throughout and in which:
field but from a point lying at the margin of
the picture field. A band at the margin of the
screen e. g. being seen comparatively greater
from the margin of the picture iield than a mid
dle band, this lateral band will predominate in
its color towards the margin of the taken or
printed or projected picture. Quite the contrary
results, if a lateral band is seen from the margin
of the picture field comparatively smaller than a
Fig. l is a diagram-illustrative of they principle
of the optical systems comprising an objective, a 2o
rection.
Ii the multicolor screen and the adherent dia
phragm are mounted in the interior of the ob
middle
band.
`
,
,
`
.
These dominants may be avoided by the known
v'means
providing a diaphragm remote from the
30
'
diaphragm and a screen, the screen being dis
tant from the diaphragm;
;
_ Fig. 2 shows a sectional side view of such an
optical system;
y
Figs. 3 and 4 are illustrative of the defect, 25
which is to be observed with the existing objec
tives making them inappropriate for use with
lenticular ñlms;
,
4
Figs. 5-10 are diagrams of different color
The fault caused'by the distortion is even
_stronger if diaphragm and multicolor screen are
screens embodying the invention.
30
In Fig. l the film is situated at I. The image
of the diaphragm seen from the film (the pupil
of emergence of the objective) is indicated by 2,
the image of the screen seen from the iilm being
placed at 3. The image of the screen is situated 35_
separated. With'such objectives the filter con
in the iinite. However, the following considera
screen, which is only eiiîective for such parts of '
the beam of light which go towards or away
from the margin of the picture iield.
` sists of a great number of bands, the colors of
which periodically repeat. A multicolor screen
with the three elementary colorsred, green and
40 blue being taken as basis„the three middle bands
may be continued by two other bands also with
the colors red, green or blue on vevery side of the
screen, the colors recurring cyclicly over the whole
ñlter. The diaphragm should be shaped in this
case -in such a manner, that the ratio of the
areas of different color seen from different points
of the picture field is constant. The diaphragm
eßg. may have a'rectang'ular shape and may
be chosen Aso wide, that the three middle bands
of the color illter are to be seenlfrom the mid
dle of the picture field.
Four diiierent bands _
are generally seen from the points lying beyond
the middle of the picture iield, two bands hav
lng-the same color. These bands shall supple
ment one another in the amount of their whole
tions are exactly the same, if the image of the ‘
screen is placed in the infinity. From the point 4
lying in the middle of the iilm gate the three
middle bands G, R, B of the iilter 3 will be seen 40
through the pupil 2, which for` instance may have
a rectangular shape.
From a point 5 on the mar
gin of. the ñlm gate instead of the band B the
band B1 of the same color-is visible and of the
band R only apart, but therefore the band R1 45
will be seen. If` for instance a hexagonal di
aphragm is used instead of the rectangular di
aphragm, the bands G and B are to be seen from
the point 4 cut in the height in diagonal direction
and therefore edges Aoi.' the bands B1 and G1 are
visible.
_
In Fig. 2 an objective is represented, the pupil
and the image of the screen having the same
position as in Fig. l. The objective .6 in the inte
rior contains the diaphragm 1, which is to be seen 55
2
2,022,978
from the film at Áthe place 2. Before the objective
other- side. At ñrst the color determined by G is
there is situated a color screen 8, which seen from ’ predominating, and on the margin the color of
the band R1 predominates again.
the iilm seems to be placed at 3.
~`
Hitherto the wide of the filter bands and the
aperture and shape of the pupil 2 were only chosen
accordingy the method illustrated `in Fig. 1.
This method however is not sufficient, and de
fective objectives are produced'. The diaphragm
"1 being placed in the interior oi the objective and
for instance having a rectangular shape, it is not
seen from the film 2 as rectangular but Aas_a
quadrangle with crooked lines. In Fig. 3 the
bands R1, B1, G, R, B, G1, R: are shown in a front
view.
The color screen being seen in this ex
~
'I'he defects arising with the screens ,known
hitherto were explained above by the example of 5
an objective, comprising a color screen, which
consists of seven different bands.l The defects
are the same, if. the screen consists of more or
less differently colored bands. If the distortion
of the pupil seen from the ñlm is not cushion-like
as illustrated in Fig. 3, but if it is barrel-shaped,
the preceding facts are also unchanged in prin
ciple.
For removing the defects described above di
ample through the whole objective, these bands
aphragms or diaphragming means are used.
appear wholly 'or at least approximately undis
torted. From the point 4 of the hlml gate that
These are preferably arranged immediately on
the color screen. Fig. v‘5 representsva front view
of the means which, though'not wholly removing
the defects, considerably reduce them. The
opaque strips of the color screen represented in 20
Fig. 5 being arranged between the single bands
part of the color screenvis visible, which consists
of the quadrangle 9 with'crooked lines. `It is evi
20 dent, that the whole visible area of the bands _G
and B is little greater than the visible area of the
band R. Beyond thislittle parts of the bands~B1
and G1 are to be seen. Looking through theob
jective from a. point out of the optical axis for
25 instance point 5, that part of the color- is visible,
which is represented by the quadrangle I0. 'I'his
quadrangle is distorted in quite another way than
the quadrangle 9. Thus, the band G1 is Vseen
greater than forinstance the band B, and the
'30 whole area visible of the bands R and Rz is still
greater.
»
~
For these parts of the ñlm gate the color deter
mined by R will considerably predominate. In
the same manner the same color predominates for
35 a point situated on the opposite side of the film
‘.gate; However, for an interiacent point of the
picture ñeld, from which the bandsRi or R2 on
the margin ofthe color screen are not yet to be
seen, the <colors predominate, which are deter
40 ' mined bythe bands B1‘or G1. It is evident, that
>a change of the ydifferent predominating colors
of the color screen, have a different width. 'I'hey
are comparatively narrow between the bands G,
R, and B and only of such a width, that the
undesirable diiîusion between the parts' of the 25
photographic layer appertaining to the different
bands of the screen is reduced to a tolerable '
degree. However, the strips between the bands
on the margin of the screen have a much greater
width, the curves 1', g, and b represented in Fig. 4 80
thereby being leveled down. 'I'he course of these
curves is influenced in such a manner, vthat they
are partly positive and partly negative and run
closely to the abscisse axis.
'
Another means which removes the dominants 85
with greater success is represented in Fig. 6.'
, Thisñgure sho-ws a sectional view. of a color
screen consisting of seven bands. Grey-wedges
K1 to K4 are laid on the bands R1, B1, G1, and R2.
y The course of the characteristic curves of those 40 '
wedges is easily chosen in such a manner using
results in advancing in lateral direction over the l the curves represented in Fig. 4 that no color
picture held.
Y
The manner in which this change proceeds is to
45 be understood from Fig. 4. In this ñgure the ab
scisses represent the distances of the points of
falsiiications arise, the curves r, g, ‘b of Fig. 4 ‘
becoming completelyrectilinear. To avoid anun- .
desirablel prism effect the part .left free between 45
the wedges R1 to R11 should be covered by a
the ñlm gate from the perpendicular through the lay'er_„S of clearly transparent material. More
middle of the gate (parallel to the direction of the over, with theseand also with the other color
The three curves r, g, and b illus-`y _ screens which should be made according to the
` color bands) .
trate which parts of the areas of the color screen invention all means known in manufacturing 50
are to be seen from'the points of the film gate.
The portions ot red, green and blue light effective
for the middle of the ñlm gate are subtracted, the
curves'only representing the difference from the
.i proportion of the bands'of different colors in the
middle of the iilm gate. The meaning of the
screens may be applied.'
For instance, opaque -
stripstmay be included between the color, bands
and cover-glasses &c. may be used.
'
'
Another modiñed color screen is shown in Fig. 7 '
in a sectional view. For the sake of an easier 55 »
manufacture the grey-wedges K2 and K3 of Fig. 6
curves is as follows: vAdvancing from the middle ' are replaced by two grey-screens L2 land La in
of the ñlm gate towards the margin, for instance
to- the point l I, the equal area 'of the bands of the
colors determined by G and R is seen as from the
y form of steps.
Moreover grey-screens L1 and Li are arranged
l on the bands>R1 and R2. y The whole is covered 60 *I
~_
~
(
- with a layer S of transparent materialto obtain
However a much greater part of the area of. the an exact paralellism of the faces of the screen.
color indicated by B is to be seen, and the differ
The same effect which is obtained with the y
ence from the middle of the illm gate amounts to' “screens represented in Figs. 6 and '7 should be
nearly 5% at point Il. In agreater distance reached to a certain degree by giving a greater 65
from the middle of the gate the vsurplus portion transparency to the bands on which the grey
of the color determined by B continually increases
middle of the ñlm gate.
65 1
areofarranged.
the grey
and reaches nearly 10% , ñnally diminishing again. . ivedges
\ Instead'
screens diaphragms ac
cording to Figs. 8 and 9 may be used. 'I'hese ñg
ures show front views of color filters embodying 7°
'I‘here a predominating of thefcolor determined by
70 R ls to -be observed, as it is shown by Fig. 3. The
-bands of the >color determined by R will be seen., the invention. The bands R1, B1, G1, and Rz of '
' on the margin with a much greater area than from Fig. 8 are covered with tapering diaphragms
the middle.
^
_
.
1
M1 to’M4. These should be made of an opaque
There are the same proportions in advancing material, for instance cut out of black paper and
from the middle of the ñlm gate towards the the like and pasted on the bands. They are ar- 75
3
2,022,978
vranged on the bands in middle height for being
and comprising recurrent series of zones of dif
also visible and effective for the points on the
ferent color values, the sum of the values in any
upper and the lower margin of the ñlmgate.
Sometimes it should be advantageous to provide
one series giving substantially the effect of white
light, and masking means applied to certain of
said zones, said masking means being so arranged
and constituted that the product obtained by
on the screen not only one but several of the
tapered masks. Such a filter‘consîsting of six
bands is shown in Fig. 9. Tapered diaphragms
multiplying the area of any zone by its trans
C-f the ñlm gate. The diaphragms should be ar
parency is constant, as viewed from different
points on the ñlm used with the objective.
3. An optical system for use with Ienticulated
ñlms comprisingA an -objective and a diaphragm,
a color ñlter spaced from the diaphragm and
comprising recurrent series of zones of different
ranged in such a manner that they are visible
color values, the sum of the values in any one
from all points.
series giving substantially the effect of white
light, and masking means applied to certain of
. M1 to M4 and M1’ to M4’ are arranged two by
two on the bands R1, B1, G1 and R2. -To show
in which circuit the masks have to be arranged
on the bands, the part of the screen is repre
sented Which is visible from a point in the corner
Instead of the masks represented in Fig. 9 a
great number of very thin and tapered dia
said zones, the amount of masking effected on
the various zones progressively increasing from
at the same distances over the length of the the center of the filter towards the edge zones.
4. An optical system for use with lenticulated 20
to be covered. If the number of the masks
20 bands
is great enough, the eifect is similar that of a- ñlms comprising an objective and a diaphragm,
grey-wedge laid on, and no defect arises if from a color ñlter spaced from the diaphragm and
each point of the ñlm gate only a part of the comprising recurrent series of zones of different
color values, the sum of the values in any one
masks of each band is visible.
,
With the examples described above it has been series giving substantially the effect of white 25
25
' suggested, that the distortion o'f the diaphragm light, and masking means applied to certain of
seen from the nlm-gate is cushion-like. If the said zones and comprising wedge-shaped dia
phragms should be used and vshould be arranged
distortion is barrel-shaped, the defects produced
by it should be eliminated. by arranging the di
30 aphragms not on the bands on the edge but on
Such a color screen, the middle bands of which
are diaphragmed, is shown in a front view in
,
5. An optical system for use with lenticulated
ñlrns comprising an objective and a diaphragm,
a color illter spaced from the diaphragm and .
Fig. 10.A
The bands G, R, and B are covered ,in the
middle by the masks M5, M6, and M7. ` Instead of
these masks the other means represented in Figs.
5. to 9 may be applied.
`
The scope of the invention has been illustrated
40 above for such optical systems, with which a color
screen consisting of one or more bands is as
sociated with the objective. However, the inven
tion also comprises optical systems used in copy
ing, a diaphragm being arranged at the place
of the color screen.
zones and applied to the zones which appear
to be too great because of the distortion of the 30
objective.
Athe middle of the screen.
35
phragms varying in width transversely of said
comprising recurrent series of zones of different 35
-color values, the sum of the values in any one
series giving substantially the effect of white
light, and masking means applied to certain of
said zones and comprising wedge-shaped dia.
phragms varying in opacity transversely of said
zones and applied to the zones which` appear to
be too great because of the distortion of the
objective.y
6. An optical system for use with lenticulated
This diaphragm may be used ' films comprising an objective and a diaphragm, 45
for copying with diiferent intensity the colors be
a color,- ñlter spaced from the diaphragm and A
longing to the different bands. In this case the
diameter of the aperture of the diaphragm should
comprising recurrent series of zones of different
not be chosen only proportionally to the >quanti
50 ties of light which are to be used in ` copying,
but it has to be taken into account that the shape
~of the aperture is changed by the distortion.
I claim as my invention:
color values, the sum of the values in any one
series giving substantially the effect of white
light, and masking means applied to certain of
said zonesy and comprising Wedge~shaped dia
phragms varying in width and'in opacity trans- y
versely of said zones and applied to the zones
which appear to be too great because ofthe
55
distortion of the objective.
’7. An optical system for use with lenticulated
a color filter spaced- from' the diaphragm andl
comprising recurrent series ofzones of different films comprising an objective and a diaphragm,
color valuesfthe sum of the valuesl in any oneA a color ñlter spaced from the diaphragm and
serie‘s `giving substantially the effect of white comprising recurrent series of zones of different
A60 light, and masking means applied to certain of color values, the sum of the values in any one 60
said zones, the amount of masking effected on series giving substantially the eifect of white
the various zones progressively changing from> light, and masking means applied to certain of
the center of the ñlter towards the edge zones. said zones and comprisingv a plurality of dia
2. An optical system for use with lenticulated phragms applied to one or more of said zones
1. An optical system for use with lenticulated
55 ñlms comprising an objective-and a diaphragm,
ñlms comprisingA an objective and a diaphragm,
a color ñlter spaced from the diaphragm
and extending transversely thereof.
'
KURT RÄNTSCH.
65
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