Improvements in Photographic Shutters.
Year: 1888

page_text: Date of Application, 28th Nov., 1888
Complete Specification Left, 12th Aug., 1889-Accepted, 28th Sept., 1889
PROVISIONAL SPECIFICATION.
Improvements in Photographic Shutters.
I, GEORGE SYLVESTER GRIMSTON, of Claremont, Glenluce Road, Westcombe Park,
Greenwich, S.E. in the County of Kent, Engineer, do hereby declare the nature of
this invention to be as follows:-
This invention has for its object the improvement of instantaneous or time shutters
for Photographic purposes, and consists mainly in the construction and arrangement
of the releasing and detaining mechanism; and is applicable to those shutters which
have a reciprocating action of the sliding shutter, and also to those which have a
revolving action of the shutter, and can be applied to those Shutters which are situated
outside the lens combination as well as to those which are used within the lens
combination.
In applying this invention to a reciprocating shutter, in which the reciprocating
action of the sliding shutter is caused by the revolution of a crank or similar device
actuated by a spring. I use a crank plate or disc to which the sliding shutter is
attached in the usual way by means of a crank pin. On the edge of this crank plate
are placed notches or detents for holding or detaining the sliding shutter, two notches
for holding it when set ready for action, and one for detaining it when fully open.
This latter notch can be used for holding the sliding shutter when fully open for
focussing. These notches will be hereinafter called Nos. 1, 2 and 3 according to the
These notches
order in which they come when setting the shutter ready for use.
engage with a pin on a lever connected with a pneumatic pump or other device for
actuating the lever. The pin on the lever being kept up against the disc when the
lever is in its normal condition by means of a spring. From notch No. 1 to notch
No. 2 a thin strip of metal forming a guide extends round the outside edge of the
aforesaid crank disc, and at such a distance from it as to allow of the said pin passing
freely between it and the disc. This strip leaves off just short of notch No. 1 and
has its end there slightly turned up towards the disc. Notch No. 3 is just beyond
notch No. 2 (these two being diametrically opposite on the crank disc to notch No. 1)
and has its edge at the same distance from the centre of the crank disc as the outside
of the aforesaid metal strip.
The action is as follows, If it is desired to give an instantaneous exposure the crank
disc is turned round until the pin on the said lever engages into notch No. 3, on dis-
engaging the pin from this notch the disc begins to revolve, and the said metal strip
comes between the pin and the disc, thus preventing the pin from engaging into
notches Nos. 1 and 2. Consequently the disc performs a complete revolution opening
and closing the sliding shutter. If now it is desired to give a lengthened exposure
the crank disc is turned round until the pin on the said lever engages into notch No. 2.
On disengaging the pin from this notch, the pin pressed by the said lever endeavours
to.force itself further away from the disc but is detained by the said metal strip, which
as the disc revolves delivers the pin into notch No. 1 which thus holds the sliding
shutter open until a second pressure on the lever releases the pin when the disc com-
pletes its revolution and closes the shutter. If before the pin is delivered into notch
No. 1 by the said strip there should be any pressure on the said lever, the end of the
strip being turned up as aforesaid prevents the disc from revolving when the pin
reaches this turned up end until such pressure is relieved, when the pin is delivered
into notch No. 1 as aforesaid. In order to diminish the shock or jar when the said
notch No. 1 hits against the said pin the lever is mounted on a spring, thereby acting
as a buffer.
In applying this invention to a revolving shutter the said disc forms the shutter,
having an opening in it for giving the exposure, the notches and strip being arranged
in the same manner as for the reciprocating shutter hereinbefore described.

page_text: It will thus be seen that when the apparatus is set for an instantaneous exposure
one pressure on the lever causes the shutter to open and close rapidly. And if set for
a lengthened exposure one pressure opens it and it remains open until the second
pressure releases it and the shutter closes.
Dated this Twenty seventh day of November 1888.
COMPLETE SPECIFICATION.
Improvements in Photographic Shutters.
1, GEORGE SYLVESTER GRIMSTON, of Claremont, Glenluce Road, Westcombe Park,
Greenwich S.E., in the County of Kent, 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 has for its object the improvement of instantaneous or time shutters
for Photographic purposes, and consists mainly in the construction and arrangement
of the releasing and detaining mechanism, and is applicable to those shutters which
have a reciprocating action of the sliding shutter, and also to those which have a
revolving action of the shutter, and can be applied to those shutters which are
situated outside the lens combination, as well as to those which are used within the
lens combination.
In order that my invention may be more fully understood reference will be made
by letters and figures to the accompanying drawing in which Fig. 1 is a front, and
Fig. 2 a side elevation of a reciprocating action shutter constructed according to my
patent for working within the lens combination in the diaphragm slot.
The drawings show the shutter set ready for a prolonged exposure.
In this shutter the reciprocating action of the sliding shutter A is caused by the
revolution of a crank disc B, actuated by a spring C, the sliding shutter being
attached to the crank disc B by means of a pin D; on the edge of this crank disc
are placed notches or detents 1, 2, 3 for holding or detaining the sliding shutter A.
Notches 2 and 3 are for holding it when ready for action, and notch 1 for focussing
and exposing. These notches engage with a pin E on a lever F preferably connected
with a pneumatic pump G, the pin E being kept up against the disc B when the lever
is in its normal condition by means of a spring H. A thin strip of metal I forming
a guide extends round the outside edge of the aforesaid crank disc from notch 1 to
notch 2, and at such a distance from it as to allow the pin E to pass freely between it
and the disc. This guide leaves off just short of notch 1, the end at this place being
slightly bent towards the disc B, as shown in Fig. 1. Notch 2 is slightly nearer to
the centre of the disc B than notch 3. The guide I is bent opposite notch 2 so that
its outside edge is at the same distance from the centre of the disc B as the point K
formed by the notch 3.
The action is as follows, if it is desired to give an instantaneous exposure the crank
disc B is turned round until the pin E engages into notch 3. On disengaging the pin
from this notch the disc begins to revolve under the action of the spring C, and the
strip or guide I comes between the pin E and the disc B thus preventing the pin from
engaging into notches 1 and 2, consequently the disc performs a complete revolution
opening and closing the sliding shutter A. If now it is desired to give a lengthened
exposure the crank disc is turned round until the pin E engages into notch 2. On
disengaging the pin from this notch the disc begins to revolve and the guide I delivers
the pin into the notch 1. If from air in the pump, or from any other cause the pin
has a tendency to force itself against the side of the guide I then its turned up end
at notch 1 holds the pin until the tendency is overcome, when the pin will be delivered
into the notch 1 as aforesaid, thus holding the shutter open until a second pressure
on the lever F releases the pin E when the disc completes its revolution and closes the
shutter.
In order to diminish the shock or jar when notch 1 hits against the said pin E the

page_text: lever F is mounted on a spring L which acts as a buffer. For stopping the disc B
at the end of its revolution a pin N is provided which in revolving in the direction of
the arrow strikes against the spring stop O thus diminishing the shock.
For altering the tension of the spring C a small spring arm M is provided so that
by turning it to the right or left the spring C is wound up or unwound.
In applying this invention to a revolving shutter the said disc forms the shutter
having an opening in it for giving the exposure, the notches and guide being arranged
in the same manner as for the reciprocating shutter hereinbefore described.
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
:
First In photographic shutters the arrangement and combination of the
notches 1. 2. 3 and the guide I for giving an instantaneous or prolonged exposure,
substantially as hereinbefore described and illustrated by my drawings.
Second: In photographic shutters the general combination and arrangement of parts
substantially as hereinbefore described and illustrated by my drawings.
Dated this 10th day of August 1889.
GEO. S. GRIMSTON.