Improvements in Photographic Shutters.
Year: 1899

page_text: Date of Application, 28th Mar., 1899
Complete Specification Left, 23rd Dec., 1899-Accepted, 28th Mar., 1900
Improvements in Photographic Shutters.
I, JOHN EDWARD THORNTON, of Rokeby, Oldfield Road, Altrincham, in the
County of Cheshire, Manufacturer, do hereby declare the nature of this inven-
tion to be as follows:-
This invention relates to pneumatic apparatus for controlling the length of
time of exposure in photographic shutters,
Pneumatic apparatus for this purpose usually consist of a cylinder and piston
or plunger, the latter being drawn out before exposure, and allowed to return
upon release of the shutter, and the length of time occupied in its return (which
indirectly controls the length of exposure) is determined by the admission of
air to or from the cylinder.
The objection to devices of this class is that it is difficult to get a good and
accurate fit between cylinder and piston, and consequently there is either con-
siderable leakage of air or else jambing of the piston in action.
The purpose of this invention is to overcome these objections and produce a
simple and certain pneumatic time controller.
In carrying out this invention I make use of rubber or similar flexible
bellows, reservoir, or equivalent. This takes the place of cylinder and piston,
and operates in a similar manner. It may be enclosed in a metal, vulcanite,
or similar tube or cover. The body of the bellows may be made of flexible
material, joined to ends of metal, vulcanite, or the like; or it may be made
throughout of the rubber or other similar material.
One end or other convenient part of the bellows, is provided with a small
hole for the ingress or escapement of air, and this may be varied in size by an
adjustable valve or other means. This enables the bellows to work at different
rates of travel.
Or the air hole may be of fixed dimensions, in which case the bellows would
always have a fixed rate of travel, and it is then convenient to use an adjustable
stop on the bellows wherewith to adjust the time of exposure.
Or the bellows may be divided into two or more chambers, the air hole or
valve making communication between them, so that in operation the air escapes
from the full to the empty chamber.
This valve may be constructed so that the air may pass very rapidly in one
direction and slowly in the other.
The bellows may be connected with the other parts of the shutter in any
suitable manner.
Dated this 27th day of March 1899.

page_text: sides of the air receptacle g being at the same time expanded and filled with
air. When released the spring o acts against the pressure of the air in the
flexible air receptacle g compressing it and driving it out of the orifice j
the size of this orifice determining the duration of time for the movement of the
spring.
In a modified arrangement shown in Figs. 8, 9, 10 and 11 the spring o may
be replaced by a second flexible air receptacle r the air being caused to pass
from one receptacle to the other. The two flexible air receptacles 9 and rare
attached to a central blocks with guide pins at each side which slide up and
down in a slot in the exterior casing. The blocks is moved upwards to set
the apparatus the air is expelled from the receptacle r and enters the recep
tacle through perforations u in a tube t as shown in Fig. 8. A cap is
secured upon the outer case or tube i forming a chamber in which is a flat disc
valve v held down by a spring forming a non-return valve. The tube is fitted
at its upper end with a slit or slot inside a sleeve and at its lower end with the
perforations u the end of the tube being plugged and screwed into the casing i.
The blocks slides upon the tube and the tube can be rotated by turning the
lower part of the case or tube i which is fitted with a spiral groove w engaging
a pin to cause it to move longitudinally.
In operation the flexible receptacle is filled with air or liquid preferably
air the block s is raised forcing the fluid out of the receptacle into the
receptacle g through the outlet orifices and non-return valve v. The block s
is held in this position by the stop catch (e Fig. 1) on the shutter, and when
it is released is drawn down by the spring o the fluid being forced from the
receptacle 9 through the perforations u into the tube t and through the longi-
tudinal slot or orifice j at the upper end. The time occupied by the fall or
traverse of the block is varied by adjusting the slot j to extend more or less
through the sleeve j¹ in which it is placed."
In another arrangement shown in Figs. 10, 11 & 12 the central blocks to
which the two flexible air receptacles y and rare attached is fixed to the body
of the shutter and the frame or case i is attached to the ends of the flexible
receptacles gand and moves up and down with them. An orifice k is placed
in the blocks closed by a non-return valve on top and an orifice is controlled
by a tap or valve m. The valve m is similar to that shown in Figs. 5 and 6
and is provided with an index wheel or knob n. The frame or case i slides
in guides attached to the shutter.
In another modification the variation of exposure may be regulated by a
device independent of the orifice as shown in Fig. 13 the casing i enclosing
the air receptacle g may be fitted with an adjustable stop I arranged with a
screw thread to adjust its position so that it may act on a roller releasing lever,
at any desired time after the apparatus itself is first released the casing i
always falling a given distance in the same time.
The apparatus shown in Figs 8, 10 and 11 is held in the position by a stop
or catch on the shutter (such as e Fig. 1) and when released is drawn down
by the spring o compressing the receptacle g and forcing the air out of it
through the orifice j into the receptacle r.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1
1. A pneumatic timing apparatus for photographic shutters constructed with
a flexible receptacle for air or fluid of bellows form with an adjustable orifice
through which the air passes to determine the speed of movement substantially
as described.
2. A pneumatic timing apparatus for photographic shutters constructed with
a flexible receptacle for air or fluid of bellows form with an orifice through
which the air passes and an adjustable stop or catch on the apparatus to alter
or determine the time of release substantially as described.

page_text: .
3. A pneumatic timing apparatus for photographic shutters constructed with
a flexible bellows shaped timing device of rubber or other material in combina-
tion with an actuating spring and an adjustable orifice through which the air
passes in or out to determine the speed of movement substantially as described.
4. Pneumatic timing apparatus for photographic shutters constructed substan- 5
tially as described with reference to either of figs of drawings.
1 1
1000
WM. P. THOMPSON & Co.,
6, Bank Street, Manchester, Patent Agents.