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Патент USA US2133994

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Oct, 25, 1938.
' M, A LAABS
2,133,994
OPHTHALMIC LENS
Filed Aug. 22, 1955
2 Sheets-Sheet l
v
INVENTQR
MAX ll. 1.191955 .
Oct. 25, 1938.
M. A. LAABS ‘
2,133,994
OPHTHALMIC LENS
Filed Aug. 22, 1955
2 Sheets-Sheet 2
175.11 P15H
INVENTOR
M/i/Y ? 09/955
v
AT
RNEY
Patented Oct. 25, 1938
I I $2,133,994
UNITED STATES PATENT * err-ice
2,133,994
‘
OPHTHALMIC LENS
,
IMax A."Laabs, Southbridge, Mass., assignor ‘to,
American Optical Company, Southbridge,
Mass, a voluntary association of Massachusetts
Application August 22, 1935, Serial No‘. 37,348 '
4 Claims.
(Cl. 88-—54)
This invention ‘,relates'to‘ ‘improvements in tri
Fig. VI is a front view of a one piece blank
focal lenses and to an improved method‘of mak
showing a stage in the process;
,
'
.,
ing the
same.
b
‘
'
.
.
A principal object of the invention is to pro
vide an improved composite one piece and fused
form of lens whereinthe fused portion of the
lens is covered andprotected from injury during
‘ the later ?nishing operations required to produce
the ?nished lens. v
v
(
vAnother object'ofthe invention is to provide
an easier and moreeconomical method for pro-'
ducing a combined one piece and‘fused lens of
this character.
1
,
'
change, in curvature.
Anotherobject of the invention is to provide a
trifocal lens wherein the softer lens medium of
the fused portion is covered .over and protected
.111) by the harder lens medium of the'outer portion.
Other objects and advantages of the, invention
will become apparent from the following descrip
tion taken in connection with the accompanying
drawings. It is apparent that many changes
I» in the details of, construction and arrangement.
of parts and the steps of the process may be made
without departing from the spirit of the inven
tion as expressed in the accompanying claims.
I, therefore, do not wish to be limited to the exact
.5 0 arrangements and ‘details shownand ‘described,
as the preferred forms only are shown and de
scribed by way of illustration.
.
In the past, when composite one piece and
fused trifocal lenses have been made, the softer
lens material of the fused portion has been ex
posed, and it has, therefore, been dif?cult and ex
pensive to'?nish the other ?elds of the‘ lens with
out marring or destroying’the fused ?eld. In my
invention the fused ?eld is buried in and covered
Vin) over by the material of the base or supporting '
‘
_
‘
Fig. VIII is a front view'of the blank showing *5
the countersink with fused ‘portion; “
Fig. IX is a cross-section on line IX-IX of Fig.
VIII;
'
'
Fig. X is a cross-section similar to Fig. IX
showing the button portion ?nished to ?nal curv- =10
ature;
Fig. XI is a cross-section showing one form of
the
‘ Another object ofthe invention is to provide a
' trifocal lens having three ?elds ‘with only one
button;
“'
'
'
t
_
‘
'
'
Fig. XII is a cross-section showing another
form of button; and
'
115
Fig. vXIII is a frontview of a ?nished blank
indicating in dot and dash lines the?nished lens
to be cut thereupom "
'
Referring to the drawings, wherein like refer‘
ences indicate correspondingparts throughout, I 320
?rst mold a dish shapedlens blank ! to'approxi
mately the general shape required for the ?n
ished lens. On oneface of therblank l, I grind
and ?nish the surfaces 2 and 3yto different curva
tures as required by the ?nished lens, the CuI'Vaj-{g5
ture 2 being used for “distance vision and the
curvature 3 for'near or reading‘vision. The op
eration of producingv these surfaces 2 and 3 is
that of the prior art ring tool method. Surfac
ing and grinding tools of ring form or of SOIldfgg
spherical form may be used, both forms of grind
ing being usual in‘the prior art.
I next grind and" ?nish the countersinkl 4
on the surface side of the blank 'I. As shown in
Fig. VIII, it will be noted that the countersink 4 1335
overlaps the inner surface 3 of the'blank. ‘These
two surfaces maybe related in any relationship
desired for the ?nished lens. The bottom of the
countersink ‘ii is‘ a spherical lenticular surface.
I next make the button 6, Fig. XI to ?t the am
lens, which has a harder lens material, and is thus
countersink 4.
protected during the ?nal ?nishing operations.
button‘ 6 has an outer portion 1 which is. of ‘the
same index of refraction as the blank I, and has
This makes a much easier job and a much ‘more
economical one to produce, and also prevents a
large percentage of the wastage which was pres
ent in the'manufacture of prior art trifocals.
Referring to the drawings:
'
Fig. I is a front view of the trifocal provided
by the invention;
'50
Fig. VII is a crossesection on line VII-VII of
Fig. VI;
'
.
Fig. II is a cross-section on line II--II of Fig. I;
' Fig. III is a front view of a modi?cation;
Fig. IV is a front view of still another modi?
cation;
'
Fig. V is a front View of still a third modi?ca
tion;
a
In‘ one form of my‘invention the '
an inner button portion 8 fused therein.
This
inner button portion 18 is of- a ‘different index of .145
refraction from that of the blank I.
_
I then ?nish the inner side of the ‘button 5
to the surface 9 to ?t the curvature 15 of the
countersink ‘Land then I fuse the button 6 in
the countersink ll, with the surface 9 engaging 150
the surface .5.
If this type of button 6 is used, ‘
the button portion‘ Swill be circular .in outline,
as shown at ‘iii in Fig. VIII. If I desire to use
a different shape of button portion 3, as shown
in Figs. III, IV, and V; Imake the button por- 555
2.
2,133,994
tion 8 in two parts, H and I2, Fig. XII. In this
form of button the outer portion 6 is of the same
index of refraction as the blank I. and the
upper portion II of the button 8 has the same
index of refraction as the part I, and the lower
portion I2 of the button 8 is of different index
of refraction.
In this way I can obtain any of
cause the fusible lens material of the portion 8
is softer than the portion I. This process, by
protecting the portion 8, is much more economi
cal and easier to perform than prior art proc
esses of making trifocal lenses of this kind, and
the percentage of waste is greatly reduced be
cause the portion 8 is not damaged during the
the shapes of the button or segment as shown
?nishing operations.
usual in fused lenses of the prior art.
After I have fused the button 6 into the coun
advantages.
Having described my invention, I claim:
1. A multifocal lens having an upper distance
?eld, central intermediate ?eld and a lower read
ing ?eld, said distance ?eld comprising a unitary
piece of lens medium of a given index of refrac
tion and having curved optical surfaces on the
opposed sides thereof of such radii as to produce
the power desired of said distance ?eld, said in 20
termediate ?eld comprising a relatively small
From the foregoing it will be seen that I have
in Figs. III, IV, and'V.
,
It will be understood, then, that in my process provided economical means for carrying out all 10
I can obtain any of the shapes of the button 8 _ of the objects of the invention and obtaining its
tersink 4, I then grind off and ?nish the project
15 ing portion of the button 6 to the surface I3,
Fig. X, which, it will be, understood, has 'now
been imposed upon the original surface 2. The
blank now will have the inner or central surface
3 as originally made, and the outer surface IS.
20 The button 8 will be buried in the material of
the blank.’ I, a portion thereof overlying the
button 8.
7
It will be noted that while the projecting por
tion of the button 6 was being ground off, the
button portion ‘8 was protected ‘and was
I25 inner
not touched by the grinding tool. This is due
to the fact that the outer portion 1 of the but
ton has the same index of refraction as the blank
I, and when they arefused together they merge
I30 so that there is really’ a portion of the same
kind of’ material as the blank I overlying the
inner button 8. This is also true in the caseof
the two part inner button 8, shown in Fig. XII,
where the part I I and the part ‘I merge with the
.
.35 material of the blank I.
After I have ?nished the blank- as described
above, and as shown in Fig. X, I next lay off the
line of the ?nished lens to be cut from the blank
as shown in Fig. X. . This is indicated by the dot
and dash line I4 in Fig. XIII.
.
.
Referring to Fig. XIII, it will be noted that
if the lens portion is cut out of the blank I along
the line I4, the portion I5 will give us the cur
vature for the distance ?eld, the portion I6 will.
give us the ?eld of the fused portion, which will
be for intermediate distance, and the portion II
of the original portion 3 will give us the ?eld for
the reading distance. It will be understood that
the portion I'I isat the bottom of the ?nished
piece of lens medium of a different index of re
fraction having curved optical surfaces on its
opposed sides and secured between the ?rst piece
of lens medium‘ and another piece of lens me 25
dium of sensibly the same index of refraction,
said ?rst piece of lens medium and piece of lens
medium of sensibly the same index of refraction
each having an outer surface which is a con
tinuationof the respective opposed surfaces on
the ?rst piece of lens‘medium and which,_com
bined with the opposed surfaces on the piece of
lens medium of a different index of refraction.
produce. the power desired in said intermediate
?eld and said reading ?eld being composed of
a continuation of the ?rst piece of lens medium
and having‘a surface on one side thereof which
is a continuation of the respective adjacent sur
face which extends over the distance and inter
mediate ?elds and having a curved surface on 40
the opposed side thereof which is of a di?erent
radius than the respective adjacent surface on
the said distance and intermediate ?elds and
which intersects said adjacent surface at a point
substantially aligned with the lower contour edge 45
-
of the piece of lens medium of a different index
of refraction, along a line substantially normal
to and extending through the plane of the lens.
2. A blank'for a multifocal lens having an up
per distance ?eld, a central intermediate ?eld and
After the blank has been out along the line I4, , a lower reading ?eld, said blank comprising a
piece of lens medium of a given index of refrac
I next grind the rear side I8, Fig. II, to a len
ticular surface of the prescription power required tion having a relatively small piece of lens medium
to give the desired prescription powers in the of a different index of refraction and provided
with curved optical surfaces on the opposed sides 55
'
55 three ?elds.
Referring to Figs. I and II, wherein the ?nished ' thereof secured to said ?rst piece of lens medium
lens is shown, the portion I3 willvrepresent' the with a piece of lens medium of substantially the
distance ?eld," the portion I6 will represent the same index of refraction as said ?rst'piece of
lens medium overlying said relatively small piece
intermediate ?eld or fused ?eld, and the por
of lens medium, said first piece of lens medium 60
tion
I‘!
will
represent
the
reading
?eld,
which
is’
.60
having two‘ adjacent surfaces of different curva
integral with the distance ?eld I3.
tures on one side thereof with one of said sur
It will be understood, of course, that the rela
tive positions of the ?elds may be changed, as faces having a radius forming a controlling ele
well as their relative sizes and shapes. It will ment of the ?nished focal power of the distance
be noted by referring to Fig. II that the fused ?eld and'overlying said relatively small piece of 65
65
?eld 8 is entirely embedded in the material of glass of a different index of refraction and func
‘the blank I, and that the ?eld I1 is integral with tioning cooperatively with the opposed curved
lens.
~
the blank I.
'
'
.
It will be clear too that in producing the lens,
70 after the button 6 has been fused in the counter‘
sink 4, the button portion 8 is’ thereafter protected during all the ?nishing operations of
making the lens. By making the portion 8 em
bedded in the portion I, the ?eld 8 is protected
75 against scratches. This is very important be
surfaces on said piece of lens medium of a dif
ferent index of refraction to produce the power
desired in the ?nished intermediate ?eld and be 70
ing so arranged as'to intersect the other ad
jacent surface of different curvature'at ‘a point
substantially aligned with the lower contour edge
of said relatively small piece of lens medium of
a different index of refraction along the line sub
76
3
2,133,994
stantially normal to and extending through the
plane of the blank and said adjacent surface of
different curvature being of such a radius as to
provide a controlling factor of the ?nished power
to which the reading ?eld is to be formed, the ra
dius of curvature of all of the optical surfaces pro
vided on the lens medium of each of said different
focal ?elds being such that a continuous optical
surface may be formed on the opposite un?nished
10 side of the blank and thereby introduce the ?nal
controlling factor of the resultant powers of the
respective focal ?elds of the ?nished lens. -
3. The method of forming a multifocal lens
having an upper distance ?eld, central interme
15 diate ?eld and a lower reading ?eld, comprising
embedding, in a piece of lens medium of a given
index of refraction, a relatively small piece of
lens medium of a different index of refraction
which has curved optical surfaces on its opposed
20 sides and the contour shape and size desired of
the intermediate ?eld, said small piece of lens me
dium being completely enclosed within said ?rst
piece of lens medium, forming, on one side of said
composite pieces of lens medium, a surface curva
ture which will function as a controlling element
of the resultant power desired of the distance ?eld
and as a controlling element of the resultant pow
er desired of the intermediate ?eld, forming a sec
ond adjacent surface on said side of the com
30 posite pieces of lens medium of a curvature dif
ferent from the ?rst curvature on said side and
which will function as a controlling element of the
resultant power desired of the reading ?eld, and
the said second surface being so formed as to in
35 tersect the ?rst surface at a point substantially
aligned with the lower contour edge of the rela
tively small piece of lens medium along a line sub
stantially normal to and extending through the
plane of the lens and forming a continuous opti
cal surface on the opposite side of said composite
pieces of lens medium of a curvature which when
combined‘with said ?rst formed surfaces com
pletes the focal powers desired in the respective
focal ?elds of the lens.
4. The method of forming a blank for a multi
focal lens which is to have an upper distance
?eld, central intermediate ?eld'and a lower read 10
ing ?eld, comprising embedding, in a piece of
lens medium of a given index of refraction, a rel
atively small piece of lens medium of a different
index of refraction which has curved optical sur
faces on its opposed sides and the contour shape 15
and size desired of the intermediate ?eld, said
small piece of lens medium being completely en
closed within said ?rst piece of lens medium,
forming, on one side of said composite pieces of
lens medium, a surface curvature which will 20
function as a controlling element of the resultant
power desired of the distance ?eld and as a con
trolling element of the resultant power desired of
the intermediate ?eld, forming a second adja
cent surface on said side of the composite pieces 25
of lens medium of a curvature different from
the ?rst curvature on said side and which will
function as a controlling element of the resultant
power desired of the reading ?eld, the said second
surface being so formed as to intersect the ?rst 30
surface at a point substantially aligned with the
lower contour edge of the relatively small piece
of lens medium along a line substantially normal
to and extending through the plane of the lens
blank and leaving an un?nished surface on the 35,
opposite side of said blank.
MAX A. LAABS.
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