Photographic and other Lenses
Year: 1888

page_text: Photographic and other Lenses.
A communication from abroad by EDWARD BAUSCH, of Rochester, in the County of
Monroe, and State of New York, United States of America, Gentleman.
I, WILLIAM PHILLIPS THOMPSON F.C.S. M.I.M.E. of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, and 6 Bank Street, Manchester, both in
the County of Lancaster, and 323 High Holborn, in the County of Middlesex, Civil
Engineer, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
This invention relates to that class of devices which are used to vary the size of,
and to open and close the opening through the lens tube, and which in their common
form consist of a series of overlapping pivoted leaves grouped around the center and
connected so as to swing inward and outward in unison.
The invention consists in an improved manner of constructing and uniting these
leaves, and in improved devices for adjusting them when used as a diaphragm, and
for operating them when used as a shutter.
In the present instance the device is shewn inserted permanently in the middle of
a lens tube, this being the preferred arrangement, but it may be constructed
independently for use in rear or in front of the lens.
In the accompanying drawings
Figure 1 is a perspective view of a lens provided with the device.
Figure 2 is a rear elevation of the device with a portion of the casing broken
away to show the form and arrangement of the leaves.
Figure 3 is a vertical axial section through the same on the line y, y of Figure 2.
Figure 4 is a face view showing the leaves as they appear when partially opened
for use as a diaphragm.
Figure 5 is a view of one of the leaves or sections detached.

page_text: Figures 6 and 7 are views illustrating the action of the devices for controlling the
movement of the lips when used as a shutter.
Referring to the drawings:
A represents the tube or mounting of the lens of ordinary construction; and B, a
ring inserted and secured in the tube midway of its length and projecting rigidly
beyond the same as shown. This ring is grooved or recessed from the interior of the
tube outward to receive the series of thin plates or leaves C, (, etc. of a curved form
such as shown in Figure 5. These leaves are grouped in a circular series around the
axis of the tube, their adjacent edges being overlapped, and their outer ends inserted
within the ring and mounted on fixed pivots b. Each leaf is provided with a stud or
projection c, which extends through a curved slot, d, in the edge of the next leaf, this
arrangement causing the leaves to swing inward or outward simultaneously and
equally. When carried to their extreme limit of movement the plates overlap in
such manner as to completely close the opening through the tube and prevent the
access of light to the lens proper. As they are turned outward they gradually
separate at the inner edges, leaving between them a central opening of gradually
increasing size in the manner illustrated in Figure 4. The studs are preferably
provided with heads or enlargement to prevent withdrawal from the slots, and each
slot enlarged at one end to permit the introduction of the head therethrough when
assembling the parts. The leaf at one end of the series has its pivot or journal
extended through the ring or support to the outside and there provided with a crank, D,
which is connected in turn by link E to a crank-pin, F, adjustably secured in a radial
slot in a rotary disk, G. This disk is supported by a journal passing through a rigid
arm, e, formed on the ring B, or otherwise suitably supported.
The rotary disk G is recessed centrally in its back to receive a coiled spring, H,
one end of which is secured thereto, while the opposite end is secured to a sleeve, I,
loosely encircling the axis of the disk, and projected through the support E, its rear
end being provided with an arm, i, the rotation of which serves to increase or
diminish the tension of the spring. The arm, i, is provided with a stud,, and the
support provided as in Figure 2, with a series of holes to receive said stud, whereby
the arm may be locked in different positions to maintain the required tension of the
spring. The disk G is provided on its periphery near the rear edge, with two studs
and, and it is also provided at an intermediate point near the forward edge with a
stud j. To the frame or other support below the disk is pivoted an angular lever of
latch, J, acted upon by a spring, l, and adapted to engage the studs hand, successively
to check the rotation of the disk G. To this lever below its fulcrum is pivoted at m,
an angular dog, n, held in place with sufficient friction to prevent its accidental
movement. The motion of this dog upon its pivot is limited by a stud, o. A piston, p,
acting beneath the free end of the latch-lever is mounted in the upper end of a tube, q,
the opposite end of which is connected as usual in this class of devices by a flexible
tube,, with a bulb or equivalent means for supplying air under pressure to lift the
piston.
The recessed crank-pin F, before alluded to, is provided with a head sliding in the
undercut slot in the disc G, and is provided on its outer threaded end with'a nut,,
by which it may be fixed in position at different distances from the centre in order to
vary the length of movement imparted to the link E.
The operation of the device is as follows:-
If it is to serve as a diaphragm, the disk is given, by means of its handle, a quarter
revolution from its normal position, or until the slot stands in a vertical position. By
this movement the link E is caused to open the leaves and provide a central aperture.
The size of this aperture may be regulated by adjusting the wrist-pin to and from
"the centre, the device thus serving the purpose of the ordinary series of diaphragms.
If now it be required to operate the device as an instantaneous shutter, the dog, n is
turned to the position shown in Figure 7, and the disk G given a half revolution
'from its normal position, until it stands as shown in Figure 1, in which position it is
locked by the engagement of the lever J against the study as shown in Figure 7.
If now the bulb be compressed, the piston will cause the lever to disengage from the

page_text: stud, whereupon the disk G, will be suddenly given a half revolution by the spring,
causing the shutter to open and instantly close again. If a time exposure be required
the dog is turned to the position shown in Figure 6, and the shutter closed as before
by turning the disk to the position shown in Figure 1. When the devices are
actuated, the disk will revolve until the stud jacts upon the end of the dog n, where-
upon it will move the dog and with it the lever, until the disk engages the second
stud , as shown in Figure 6, the effect of which will be to arrest the parts in position
to hold the shutter open. A second impulse of air will cause the dog to disengage
from the stud h and permit the disk to continue its revolution until the shutter is
closed.
In some cases the slots may be omitted and the stud C on each leaf arranged to
slide against the inner edge of the next leaf. In this case the crank will serve the
purpose simply of communicating motion through the studs to the successive leaves
to effect their outward movement, and a spring must be applied to the terminal leaf
in the series to effect the inward movement, the leaves being opened and held open
against the stress of this spring. The slotted connection is preferred as it ensures the
positive motion of the leaves in both directions.
A series of pivoted leaves grouped around the axis of a lens tube have already been
connected by intermediate links and by means of a revolving ring, but these inter-
mediate connections have not hitherto been dispensed with, nor has each leaf been
provided with a stud acting directly upon the next leaf.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by my
foreign correspondent, I declare that what I claim is :-
1. The series of pivoted leaves grouped around a central point and each provided
with a stud engaging and imparting motion to the next leaf, substantially as
described.
2. A series of pivoted leaves grouped around a central point, each leaf provided
with a stud passing through a slot in the next leaf, the series of leaves or plates
pivoted and connected as described, in combination with a crank-arm, D, the revolving
disk, its crank-pin, the connection from the crank-pin to the crank D, the actuating
spring, and a detent, substantially as described.
3. In combination with the spring-actuated disk or drum G, connected to and
operating the leaves of the shutter, the lever or detent J, and the dog n mounted
thereon: whereby the device may be adapted for instantaneous or time exposures at
will.
4. The pivoted connected leaves and their operating crank D, in combination with
the revolving disk or drum, its. actuating spring, the detent to arrest its motion, the
radially adjustable crank-pin F and connection therefrom to the crank D: whereby
the opening and closing movement of the leaves may be varied at will.
DL: 1441
1000
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
Agents for the Applicant.