Improvement in Photographic Shutters.
Year: 1889

page_text: Date of Aplication, 14th Nov., 1889
Complete Specification Left, 11th Aug., 1890-Accepted, 4th Oct., 1890
PROVISIONAL SPECIFICATION.
Improvement in Photographic Shutters.
I, HENRY GRANT MADAN CONYBEARE of "The Hut" Ingatestone in the County
of Essex, Gentleman, do hereby declare the nature of this invention to be as
follows:
This invention is an improvement in photographic shutters for making so-called
instantaneous exposures. In carrying out my invention 1 use a box preferably of
wood or other material. This box has an aperture on each side of it one of them
of such size as to fit on the front or back of the lens with which the shutter is to
be used.
In the box fit three hollow rollers preferably of brass tube.
Two of the rollers are placed at one end of the box and one at the other ond. One
of the two rollers which are placed near together contains a spring as in the spring
rollers used for window blinds. But the spring may be mado like a watch spring and
placed in a small case on the end of one of the rollers.
To one of the two rollers, at one end of the box, I attach narrow bands or strips
of silk ribbon or tape one at each end. These strips are carried to the other end of
the box and passed over the ends of the one roller, they then return to the other
end of the box and are passed once or more times round the third roller containing
the spring and the ends attached to the said roller. To these two bands I fasten a
piece of cloth, preferably mackintosh cloth, so that it comes between and just covers
the two apertures which are in the opposite sides of the box thus forming a blind.
To actuate the shutter, I turn round one of the two rollers at one end, the one
which does not contain the spring, this draws the strips or bands off the other roller
causing it to revolve and wind up the spring contained in the roller. This at the
same time draws the blind from between the apertures, over the roller, at the other
end of the box, and back, on the other side of the roller, between the apertures in
the box.
.
The rollers are then held and prevented from revolving by a ratchet and pawl
attached to the axle of one of the rollers. The rollers may be released by hand or by
a pneumatic release. The axle of the roller containing the spring may also be fitted
with a ratchet or other arrangement, enabling the spring to be wound up independent
of the blind.
The instantaneous exposure is made by releasing the ratchet, when the spring
draws the blind from between the apertures over the roller and back again, between
the two apertures in the box.
Dated this 14th day of November 1889
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvement in Photographic Shutters.
1, HENRY GRANT MADAN CONYBEARE of "The Hut" Ingatestone in the County
of Essex, Gentleman, 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 is an improvement in photographic shutters for making so-called
instantaneous exposures. În carrying out my invention I use a box preferably of

page_text: wood or other material. This box has an aperture on each side of it one of them of
such size as to fit on the front or back of the lens with which the shutter is to be
used.
In the box I fit three hollow rollers preferably of brass tube.
Two of the roliers are placed at one end of the hox and one at the other end.
One of the two rollers which are placed near together contains a spring as in
the spring rollers used for window blinds. But the spring may be inade like a
watch spring and placed in a small case on the end of one of the rollers.
To one of the two rollers, at one end of the box, I attach narrow bands or strips of
silk ribbon or tape one at each end. These strips are carried to the other end of the
box and passed over the ends of the one roller, they then return to the other end
of the box and are passed once or more times round the third roller containing the
spring and the ends attached to the said roller. To these two bands 1 fasten a piec
of cloth, preferably mackintosh cloth, so that it comes between and just covers the
two apertures which are in the opposite sides of the box thus forming a blind. To
actuate the shutter, I turn round one of the two rollers at one end, the one which
does not contain the spring, this draws the strips or bands off the other roller causing
it to revolve and wind up the spring contained in the roller. This at the same time
draws the blind from between the apertures, over the roller, at the other end of the
box, and back, on the other side of the roller, between the apertures in the box.
The rollers are then held and prevented from revolving by a ratchet and pawl
attached to the axle of one of the rollers. The rollers may be released by hand or
by a pneumatic release. The axle of the roller containing the spring may also be
fitted with a ratchet or other arrangement, enabling the spring to be wound up
independent of the blind.
The instantaneous exposure is made by releasing the ratchet, when the spring draws
the blind from between the apertures over the roller and back again, between the
two apertures in the box.
In order that my said invention may be fully understood and readily carried into
effect 1 will proceed to describe the drawings hereunto annexed.
Figure 1 is a plan (with the cover plate removed) of a photographic shutter
constructed in accordance with my invention.
Figures 2 and 3 show the opposite sides of the same.
Figure 4 is a longitudinal section.
a is the box or case of the instrument and a¹ a' are apertures in it. b c and d are
three rollers mounted in the box. The roller b contains a coiled spring. e e are
bands attached at their ends to the rollers band c. f is the piece of mackintosh
cloth which the bands carry.
g is a retaining pawl engaging with the teeth of a ratchet wheel on the axis of
the roller c. i is another retaining pawl engaging with the tooth of a ratchet
wheel on the axis of the spring roller b.
To
prepare the shutter for action the bands are wound up on to the roller cuntil
the blind is opposite the aperture a¹. The pawl g then retains the blind. Z is a
cylinder fixed to the side of the box a. By means of a flexible tube air can be
forced into the cylinder and when this is done the piston m is moved and in turn it
displaces the pawl g. The bands e e are then by the action of the spring wound upon
the roller b and the blind passes from in front of the aperture a¹ to a corresponding
position in front of the aperture a³. The rapidity of motion depends on the tension
of the spring and this can be regulated by means of the pawli and ratchet wheel k.
Whilst the blind is passing around the roller d the photographic lens is uncovered
and as will be seen the exposure commences and terminates at the same edge of
the lens.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
A photographic shutter substantially as described in which the exposure is made
by a blind drawn around a roller by a spring and so arranged that the exposure
commences and terminates at the same edge of the photographic lens as herein set
forth.
1800
CARPMAEL & Co.,
Agents for the Applicant.