Improvements in Shutters for Photographic Cameras.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in Shutters for Photographic Cameras.
We, JOHN EDWARD THORNTON and EDGAR PICKARD, of Altrincham, near
Manchester, in the County of Chester, Manufacturers, do hereby declare the nature
of this invention to be as follows:-
This invention relates to that class of shutter in which in addition to the
ordinary spring blind there is an auxiliary spring blind-which may be termed a
safety blind-for the purpose of covering the aperture of the ordinary blind whilst
being set for exposure.
The exposing blind is formed in the ordinary way with an aperture about in the
centre of it and the safety blind is formed with an opening at the top edge or with
the top edge connected to a winding roller by tapes or cords. Each blind is
attached to two separate rollers a winding roller at one end of the box and a spring
roller at the other end.
One setting cord is applied to the two blinds being attached to the roller of one
and passing round the roller of the other actuates it by friction.
On the end of the winding roller of the ordinary blind is placed a wharve or
other similar device around which the setting cord is passed with one or two turns.
One end of the setting cord is secured to the winding roller of the safety blind and
wound round upon it for several turns so that the pulling of the cord causes the
roller to rotate to wind up the blind. The cord is then passed with one or two
turns round the wharve or end of the winding roller of the exposing blind so that
when the cord is tightened and drawn off the safety blind roller it causes the
exposing blind roller to rotate at the same time. Thus by the pulling and drawing
forward of the setting cord the two blinds are caused to wind up upon their
respective winding rollers simultaneously. The cord may be attached to the
exposing blind winding roller and work the safety blind by friction, that is to say
vice versa.
When the exposing blind is set and the cord released the blind is retained in the
ordinary way in position covering the aperture in the shutter case. The release of
the cord however allows the safety blind to be immediately drawn back by and
re-wound upon the spring roller the cord being loose slips freely around the end
or wharve of the other winding roller without exerting any material friction
thereon.
We find it advantageous to pass the setting cord from the winding roller of the
safety blind down to the bottom of the box around the spring roller of the safety blind
(or around a pin or roller for the purpose) then back to the top of the box and
around the winding roller of the exposing blind instead of direct from one winding
roller to the other. The cord then works the spring roller by friction as well as
the winding roller and thereby prevents slipping during winding up. the exposing
blind and it allows the cord to wind evenly on the rollers.
Dated this 26th day of January 1895.
WM. P. THOMPSON & Co.,
6, Bank Street, Manchester, Patent Agents,

page_text: Improvements in Shutters for Photographic Cameras.
We, JOHN EDWARD THORNTON, and EDGAR PICKARD, of Altrincham, near
Manchester, in the County of Chester, Manufacturers, 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 shutter in which in addition to the
ordinary spring blind there is an auxiliary spring blind-which may be termed a
safety blind-for the purpose of covering the aperture of the ordinary blind whilst
being set for exposure.
The exposing blind is formed in the ordinary way with an aperture about in the
centre of it and the safety blind is formed with an opening at the top edge or
with the top edge connected to a winding roller by tapes or cords. Each blind is
attached to two separate rollers a winding roller at one end of the box and a spring
roller at the other end.
The invention consists essentially in so arranging or constructing the two blinds
and the setting cord that one setting cord is applied to the two blinds being
attached to the roller of one and passing round the roller of the other, actuating it
by friction so that by pulling the single setting cord the safety blind and the
exposing blind are pulled up together and when the cord is released the safety
blind returns to its roller and the setting blind is retained set until released by the
ordinary time or other releasing mechanism.
The invention will be fully described with reference to the accompanying
drawings in which the cord is shown attached to the roller of the safety blind and
in frictional contact with the roller of the exposing or ordinary blind.
It is to be
understood however that this may be reversed and the cord be attached to the
roller of the exposing blind and be passed round in frictional contact with the
roller of the safety blind.
Fig. 1. Front elevation.
Fig. 2. Transverse section showing the safety blind and the exposing blind
wound upon their respective spring rollers.
Fig. 3. Transverse section showing the exposing blind wound up for focusing
and the safety blind drawn up in front of the aperture.
Fig. 4. Transverse section showing the exposing blind wound up upon its
winding roller and the safety blind returned to its position and wound up upon its
spring roller.
The ordinary exposing blind A is constructed as usual with a central aperture
attached at one end to a spring roller B and at the other end to a winding roller C
to which is connected releasing mechanism of ordinary construction not shown in
the drawings. And the safety blind D is constructed as described in the
Specification of our former Patent No. 17,516 A.D. 1891, being connected to a
winding roller E by tapes d and to a spring roller F at the other end.
The setting cord G is at one end attached to the winding roller E of the safety
blind D and wound round it for several turns so that the pulling of the cord causes
the roller to rotate to wind up the safety blind D. The cord G is then passed
down round the end of the spring roller B and up again and round the end of the
winding roller C of the exposing blind A. The cord G is passed with one or more
turns round the end of this roller so that when it is tightened and drawn off the
safety blind roller E it causes the exposing blind roller C to rotate at the same
time. Thus by the pulling and drawing forward of the setting cord G the two
blinds are caused to wind up simultaneously upon their respective winding
rollers C and E.

page_text: If found convenient this arrangement may be reversed the cord G being
attached to the winding roller C of the exposing blind A and be lapped round the
roller E of the safety blind D and work it by friction.
The
When the exposing blind A is set and the cord G released the blind is retained
in the ordinary way in position covering the aperture in the shutter case.
release of the cord G however allows the safety blind D to be immediately drawn
back by and re-wound upon the spring roller the cord being loose slips freely
around the end or wharve of the winding roller C without exerting any material
friction thereon, and is rewound round the end of the roller E.
We find it advantageous to pass the setting cord G from the winding roller E of
the safety blind D down to the bottom of the box around the spring roller B of
the exposing blind A (or around a pin or roller for the purpose) then back to the
top of the box and around the winding roller C of the exposing blind instead of
direct from one winding roller to the other. The cord thus works the spring roller
by friction as well as the winding roller and thereby prevents slipping during
winding up the exposing blind A and it allows the cord to wind evenly on the
rollers but this arrangement is not essential to the working of the invention.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. In a photographic shutter constructed with two blinds (an exposing and a
safety blind) the combination of a single winding cord attached to the end of one
winding roller and lapped round the end of the other in frictional contact therewith
so that by the pulling of the setting cord both are set or wound up together one by
the direct pull of the cord and the other by the friction of the same cord upon its
roller substantially as described.
2. A photographic shutter having two blinds constructed with a single setting
cord arranged in combination therewith substantially as herein described and
shown.
D
0
A
WM. P. THOMPSON & Co.,
Manchester, Liverpool, and London, Patent Agents.