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Патент USA US3088379

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SR
BSO-476
OR
SEARCH ROOM
390889369
May 7, 1963
J. R. MILES
3,088,369
PROJECTION LENS SYSTEM
Filed Feb. 12, 1960
T23 Óé
IHMUNI HMW|.I
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United States Patent O ”
Patented May -7, v 1963
1
2
3,088,369
These and other features and objects of the invention
will be apparent upon reading of the specification with
PROJECTION LENS SYSTEM
John R. Miles, Glenview, Ill., assignor to
`
3,088,369
Ce.
Fred E. Aufhauser
,
Filed Feb. 12, 1960, Ser. No. 8,279
10 Claims. (Cl. 88-'57)
reference to the following drawing.
v
In the drawing:
FIGURE l is a side view in section of the lens assem
bly; and
‘
FIGURE 2 is a schematic view showing the lens adapter
This invention pertains to optical devices used in the
assembly used in conjunction with a projector and a pro
projections of images such as in motion picture projectors
jection screen.
and in particular is related to the construction of a lens 10
Referring now to FIGURE 1, there is shown the lens
adapter to be used in conjunction with the standard pro
assembly generally denoted by the numeral 10. The lens
jection lens for the purposes of magnifying the projected
image.
In the projection of an image, lsuch as in a motion pic
ture projector, ra source of light such as a large arc lamp 15
is employed.
The light from the arc is projected by
means of a mirror, s_uch as va concave ellipsoidal mirror,
assembly is composed of four lens elements 12, 14, 16,
and 18, and in which the elements 12 and 14 in one pre
ferred embodiment are cemented together to form a
doublet.
.
v
It is to be noted that the lens assembly as shown in
FIGURE 1 and as will be described hereinafter is fully.
onto the area of the tilm which is being projected. The
corrected for spherical aberrations, coma, astigmatism
projected light r-ays are then received into a projection
and distortion. In fact, the corrections of this system
lens assembly placed on the other side of the ñlm which 20 are such that there is compensation for some of the re
images the film and its picture onto the screen.
sidual aberrations in the lens assembly to` which it is at
Motion pictures, up until about 1952, were all what
tached. These compensations are such that the quality
is known today as small screen projection. Due to the
of the final projection is frequently as high as 30 percent
limitation of the projection apparatus prior to that time
4better than the projection of the lens itself. This com
it was necessary to use small screens and projecting lenses 25 pensation is in the form of an improved Petzval sum and
that had long local lengths. The focal length of the pro
compensating off-axis spherical aberration.Y
jection lenses used `in theatre projectors seldom departed
As was mentioned previously, the ñrst component 20
from the range of four inches to eight inches. When the
is a doublet which may or may not be cemented` and in
wide screen m-otion pictures started after Cinerama was
which the elements 12 and 14 are made of crown and
introduced, lenses with short focal lengths between ll/z 30 flint glass, respectively. The component 20 is of a posi
and 4 inches were tried in projectors. These short focal
tive power with the first element 12 being double con
length lenses increased the size of the picture, thus per
vex and the second element 14 being double concave.
mitting an increase in size of the screen, but the quality
The third element or second component 16 is airspaced
of the edge of the screen was relatively poor. Further
from and optically aligned with the component 20, and Y
more, the illumination fell off badly at the edge due to 35 is of a negative power. In this particular showing the.the specific geomeu'y of the arc lamp with its ellipsoidal
element 16 is of a double concave construction and is
reliector.
made of crown glass.
Several efforts were made to design and produce new
The third component or fourth'element 18 is ai-r
short focal length lenses with extremely large apertures
spaced and optically aligned with the preceding com
and high light gathering power. These elîorts took the 40 ponents 16 and 20 and is `airspaced from the former.
form of an anamorphic attachment in front of the lens
such as in Cinemascope. The anamorphic attachment
had the limitations of requiring special cameras and by
the time viewings were made through the anamorphic
units on both the camera and projector, the image suf
fered seriously from astigmatism as well as other defects.
Other elforts have been made to design attachments
or adapters to slip on the front of the lenses in order to
This component is made of flint glass and is of posi
tive power, and in this particular instance is of a double
convex construction.
4It is to be noted that certain variations may be made
in the construction of these lens elements. For exam
ple, the thickness of the lenses may vary as much as ‘
three or four units and the radii may vary in the follow
ing manner:
shorten the focal length of the basic lens. While these
units
previou-s attempts have accomplished the purpose of short 50 R11-5
Rai-100
units
ening the focal length of the basic lens, none of them
R3 £100 units
can produce an image of adequate quality nor do they
R4i25 units
R5-_t-2 units
R6i3 units
R7-l_:5 units
Rai l0 units
have -suñicient light projecting ability to make them
feasible.
l
-
Therefore, it has been necessary to design a new lens 55
adapter assembly having a primary feature and object of
The spaces may vary in the following manner:
Sl-_l-O to `3 units
82:5 units
S31-1.5 units
being adapted to be used in combination with a standard
projecting lens unit. The lens adapter assembly is fully
corrected for spherical aberrations, coma, astigmatism, 60 It is to be understood that where any of these values
in the formula are varied by the amounts indicated, tech
and distortion. Thus as a direct resul-t it produces an im
nical changes must be made in the formula which are in
age of high quality. A further feature and object of the
invention resides in provision of a lens adapter assembly
which produces an image substantially twice the size of
the scope and experience of one skilled in the art of com->
puting lenses of this nature.
4
that projected by the standard projection lens assembly. 65 The indices of refraction and the reciprocal dispersion
ratio can be varied also with the same understanding. In
Anotherl object and feature of the invention resides in
this
instance,A the index of refraction can change by
the provision of a lens adapter ~that may be used in con
i.005, and the reciprocal dispersion ratio by $1.5.l
junction with a standard projection lens without any sub
Hereafter the index of refraction yand reciprocal disper
stantial alterations of either lens unit.
sion ratios will be indicated by the’symbols ND and v.
e
s
3,088,369
Table l
[Total length of lens assembly (R1 to Ri) equals 100 units]
Lens
Radii
Spacing
Thiclmess
4
the projector. This attachment does not require any
substantial modification of the projector itself and may
be used without any special skills on behalf of the opera
ND
tor.
v
`
It is to be noted that the subject invention may be
Ri
used in combination with 16 mm., 35 mm. and 70 mm.
48.49
I ___________ _-
T1
4.27
1.511
63.5
T3
1.23
1.673
32.2
T3
1.53
1.513
60.5
Rz -548.34
S1
.
0
Ita-548.34
II .......... _.
R4 +152.73
»
R5 _31.21
S4
81.73
Sa
6.05
III ......... _.
Re +8323
IV_________ -_
Bri-104.78
f
Ria-233.93
T4
5.19
1.673
projectors and is not limited to any one particular size.
AActually the invention may be used for many types of
projectors in addition to the motion picture field and
10 with many types of photography where there is a require
ment for larger angular field.
Although certain specific embodiments have been set
forth hereinbefore, it is to be understood that these are
merely by way of example, and -in no manner to' be con
strued as limitations. It is apparent that certain modifica
tions may be made within the scope of the claims with
32.2
out departing from the spirit of the invention.
Being an afocal attachment, the focal length is infinite.
It is apparent from the preceding discussion that the
data given in Table I is merely by way of example and
is not to be construed as a limitation.
Table Il
[Total length of lens assembly (R4- to Ri) equals 100 units]
Radiî
R1
Spacing
lens assembly, respectively, and in which the fourth ele
ment is double convex with its first and second surfaces
30 having radii of curvature of .99 to 1.09 and 2.23 to 27.43
Thickness
ND
u
T4
4.27
1. 511
63.5
2. A lens assembly according to claim 1 in which said
third and fourth elements have indices of refraction of
1513:.005 and 1.673 -l_-.005, respectively, and reciprocal
T:
1.23
1.673
32.2
35 dispersion ratios of 60.5 i 1.5 and 35.881-15, respectively.
Ta
1.53
1.513
60.5
T4
5.19
1.6643
35.88
times said total length, respectively.
Ra -54834
S1
0
II ........ -_
R4 +152.73
S1
R5 _31.21
.R4 +8323
Sa
3. A lens assembly adapted for use in conjunction with
a projection lens assembly for magnifying the projected
image comprising four lens elements which have the fol
lowing constructional data:
81.73
III ....... -_
‘
R1 +104.78
IV....... _-
6.05
Ba -223.7B
40
[Total length of lens assembly (R1 to Ri) equals 100 units]
Lens
Being an afocal attachment, the focal length is infinite.
This second embodiment provides for a better color cor
rection by the choice of a different glass for constructing
the last lens.
~
the first lens element is dou-ble convex and the second is
double concave, and in which the third and fourth ele
ments are airspaced and aligned with the first and second
25 elements, and in which the third element is double concave
with its first and second surfaces having radii of curvature
of .29 to .33 and .80 to .86 times the total length of the
48.49
I .......... -_
12x-548.34
-
1. A lens assembly adapted for use in combination with-
a projection lens assembly for magnifying the size of the
These data may 20 projected image comprising four lens elements in which
be varied in accordance with the criteria set forth here
inbefore as long as technical compensations are made
for such variations.
A second embodiment of the invention is as follows:
Lens
What is claimed is:
-
ing device such as that used for projecting motion pic
tures is generally denoted by the numeral 50. The
projector 50 is provided with aA source of light 52 such
as a carbon arc or some equivalent device.
the film strip 56, and from there into the projecting lens
58 which forms the image. The subject invention 60
is attached by suitable means onto the projecting lens 58
as shown in the drawings. In this instance the invention
consists of a casing 61 which is provided with a flange
48.49
-548.34
Ra --548.34
~
R4 +152. 73
R5
Thickness
N..
v
T4
1.511
63.5
-
4.27
.
Si
Sz
`
0
II .......... _-
T1
1.23
1.673
Ta
1.53
1.5l3
60.5
T4
5.19
1.673
32.2
_31.21
R4 +8323
32.2
81.73
~
III ......... _-
The light
from the source 52 is reflected by the mirror S4 onto
Ri
Ri
Spacing
I ........... _-
45
Referring now to FIGURE 2, there is shown a schema
tic illustration of the subject invention in use. A project
Radii
Ss
6.05
R1 +104. 78
IV......... -_
Ra -23393
wherein ND and v are the index of refraction and recipro
cal dispersion ratio, respectively.
4. Inan image projecting apparatus the combination of
a projection lens assembly and a lens adapter assembly
for increasing the size of the projected image, said lens
into optical alignment with the projection lens 58. The 60 adapter assembly comprising four lens elements in which
the first lens element is double convex and the second is
lens elements 12, r14, 16 and 18 are housed within the
double concave, and in which the third and fourth ele
casing 61 and are constructed in accordance with the
ments are airspaced and aligned with the first and second
principles previously set forth. .The «imagevfrom the
or some suitable mechanical construction for grasping
the camera casing in order to place the lens elements
elements and in which the third element is double con
65 cave with its first and second surfaces having radii of
curvature of .29 to .33 and .80 to .86 times the total length
By way of illustration the image that will be formed
projector is formed on the screen 62 according to con
ventional practices.
by the standard projection element is indicated by the .
of the lens assembly, and in which the fourth element is
dotted lines 64.
double convex -with its first and second surfaces having »
The image that will be formed as a
radii of curvature of .99 to 1.09 and 2.23 to 2.43 times
result of the adapter is indicated by the dotted lines 66.
The size of the latter image, as mentioned previously, 70 said total length, and in which said third and fourth ele
ments have indices of refraction of 1.513i.005 and
will be approximately twice the size of that formed by
1.673 :.005, respectively, and reciprocal dispersion ratios
the standard projection lens.
of 60.5 -'_-1.5 and 32.2il.5, respectively.
It is now apparent that the subject invention provides
5. In an image projecting apparatus the combination of
a means for obtaining an image of an increased size as
well as of improved quality by simply ‘attaching it onto 75 a projection lens assembly and a lens adapter assembly
3,088,369
5
6
for increasing the size of the projected image, said lens
adapter assembly comprising a four lens unit having the
following constructional data:
of the projected image comprising four lens elements in
which the first lens element is double convex and the
second is double concave, and in which the third and
fourth elements are airspaced and optically aligned with
[Total length of lens assembly (R1 and R5) equals 100 units]
the first and second elements, and in which the third
Lens
Radii
Spacing
Thickness
Nn
element is double concave with its first and second sur
v
faces having radii of curvature of .29 to .33 and .80 to
R1
.86 times the total length of the lens assembly, respective
43. 49
I ......... _.
T1
4. 27
1. 511
63.5
T1
1.23
1.673
32.2
T3
1.53
1.513
60.5
T1
5.19
1.6643
35. 3s
R1 -54s. 34
It; _54s. 34
Si
0
II ........ _.
ly, and in which the fourth element is double convex
10 with its first and second surfaces having radii of curva
ture of .99 to 1.09 and 2.13 to 2.33 times said total
length, respectively.
R1 +152. 73
R1 -31. 21
si
81.73
HI _______ -_
R. +33. 23
S5
8. -A lens'assembly :according to claim 7 in which said
third and fourth elements have indices of refraction of
1.5131-.005 and 166432005, respectively, and, recip
6.05
rocal dispersion ratios of 60.5215 and 35.88115, re
R1 +104. 52
IV....... _.
spectively.
Rg _223. 73
wherein ND and v are the index of refraction and recipro
cal dispersion ratio, respectively.
6. A lens assembly adapted for use in conjunction with
a projection lens assembly for magnifying the projected
image comprising four lens elements which have the fol
lowing constructional data:
[Total length of lens assembly (R1 and R1) equals 100 units]
Lens
Radii
Ri
Spacing
Thickness
N.,
v
T1
4.27
1.511
63.5
T1
1.23
1.673
32.2
43.49
I ......... _-
Ri -543. 34
S1
9. A lens »assembly adapted for use in combination
with a projection lens assembly for magnifying the size
20 of the projected image comprising first, second and third
25
fraction of 1.513i.005 and 167312005, respectively, and
Ri -543 34
31.73
1.53
v
Sa
1.513
References Cited in the file of this patent
UNITED STATES PATENTS
60.5
,
6.05
R7 +104. 52
IV....... ._
.
`
T1
+83. 23
reciprocal dispersion ratios of 60.5215 and 35.88i1.5,
respectively.
si
III ....... _Rg
length of ythe lens assembly, respectively, and in which
the third component is double-convex with its first and
second surfaces having radii of curvature of .99 Ito 1.09
and 2.23 to 2.43 times the total length, respectively.
10. A lens assembly «according to claim 9 in which
30
said second and -third components have indices of re
0
II ........ ._
R4 +152. 73
R5 _31.21
lens components in which the second and third lens com
ponents are lair spaced and aligned with said first com
ponent, and in which the second component is double
concave with its first and second surfaces having radii of
curvature of .29 to .33 and .80 to .86 times the total
.
Ti
5.19
1. 6643
35.88
Rs -223.7s
40
2,421,927
Cox _________________ __ June 10, 1947
2,582,085
Toole ...... _; ________ _.. Jan. 8, 1952
796,445
Great Britain _________ __ June 11, 1958
FOREIGN PATENTS
wherein ND and v are the index of refraction and recipro
cal dispersion ratio, respectively.
7. A lens assembly adapted for use in combination
with a projection lens assembly for magnifying the size
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