Improvements in or in connection with Photographic Roller Blind Shutters.
Year: 1899

page_text: Date of Application, 25th May, 1899
Complete Specification Left, 22nd Feb., 1900 -Accepted, 12th May, 1900
Improvements in or in connection with Photographic Roller Blind
Shutters.
I, JOHN EDWARD THORNTON, of Rokeby, Oldfield Road, Altrincham, in the
County of Chester, Manufacturer, do hereby declare the nature of this invention
to be as follows:
The improvements forming the subject of this invention relate to the
mechanism of photographie roller blind shutters.
In these as usually constructed a flexible blind is rapidly moved through the
uncoiling of a long coiled wire spring enclosed in a barrel which forms one of
the rollers of the blind, or else a volute spring placed in a separate barrel
attached to some part of the shutter. If placed in the roller (as is usual in
blind shutters) a very long, weak, and flexible spring is sufficient to drive the
rollers and rotate them a sufficient number of times, whilst it also allows the
extent to which the spring can be wound to be varied very considerably and thus
give the shutter blind a wide range of speed and therefore similar range of
exposures, all without great jerk or concussion upon stoppage of the blind.
In the other case of a volute spring it has been found that the same range
of adjustment and flexibility cannot be got, (at any rate in the space usually
available) and whilst such springs suit some forms of shutters, the other forin
of spring already described is much superior for blinds which have a consider-
able travel.
This invention provides a means of obtaining the advantages of a long coiled
spiral spring in a different way, for shutters where the construction does not
lend itself to the spring being conveniently enclosed in the roller, and where
the volute form of spring would be unsatisfactory.
In carrying out this invention I drive the blind by means of a closely coiled
spiral spring of very small diameter and considerable length, which gives motion
to the blind by reason of the spring exerting a pull in the direction of its length,
due to its resuming (upon being released) its normal or compression state, after
having first been stretched or placed in a state of tension to operate the shutter.
This spring may be mounted or placed on the side of the shutter case or other
suitable position. One end is directly or indirectly connected to a blind roller
or rollers or to the blind itself, and the other end is connected to the case either
directly or indirectly. For instance the spring may be attached to one of the
rollers which may be termed the driving roller, or to a drum or pulley thereon,
so that the spring may make one or more turns round the roller or drum; or it
may be attached to a cord or tape which similarly winds round the roller; or to
a cord which does not pass round the roller but causes the spring itself to coil
round the roller several times instead; or to a toothed wheel, rack, or similar
device, which engages with and turns a small pinion on the end of the roller;
or in any other suitable way. The other end may be attached directly to the
case, in which instance the tension would never be increased beyond fixed

page_text: limits, or it may be connected to either a sliding or rotating piece whereby the
spring can be stretched more or less at the will of the operator, to vary its
tension and consequently the speed of the shutter.
Two or more such springs may be used (say either side by side) or separate
on opposite sides of the blind) to give a stronger pull than could be got with
one spring, unless by increasing the strength and consequently decreasing the
flexibility or resiliency thereof.
A similar spring or springs can also be used and placed so as to commence
to exert a pull in an opposite direction upon the blind (or working parts con-
trolling same) as the blind is stopped in order to take up or prevent vibration.
A spiral spring or springs such as described may be used to operate shutters
having blinds arranged in various ways, of which the following are a few, and
probably the most useful examples. The usual simple form of single blind
winding from one roller on to another; a double blind, which, in winding from
one roller on to another, passes over or around another roller or rollers, whereby
it is formed into two thickness or blinds; an endless blind; two separate blinds.
These comprise all known forms of photographic shutter blinds, including
ordinary, self capping, everset, double, rotary, single action, and reversing or
reciprocating action, but should there be any others this form of spring driving
can be used if suitable.
T
T
Improvements in or in connection with Photographic Roller Blind
Shutters.
I, JOHN EDWARD THORNTON, of Rokeby, Oldfield Road, Altrincham, in the
County of Chester, Manufacturer, 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:-
The improvements forming the subject of this invention relate to the
mechanism of photographic roller blind shutters.
In these as usually constructed a flexible blind is rapidly moved through the
uncoiling of a long coiled wire spring enclosed in a barrel which forms one of
the rollers of the blind or else a volute spring placed in a separate barrel
attached to some part of the shutter. If placed in the roller (as is usual in
blind shutters) a very long weak, and flexible spring is sufficient to drive the
rollers and rotate them a sufficient number of times whilst it also allows the
extent to which the spring can be wound to be varied very considerably and thus
give the shutter blind a wide range of speed and therefore similar range of
exposures, all without great jerk or concussion upon stoppage of the blind.
In the other case of a volute spring it has been found that the same range
of adjustment and flexibility cannot be got (at any rate in the space usually
available) and whilst such springs suit some forms of shutters the other form
of spring already described is much superior for blinds which have a consider-
able travel.
This invention provides a means of obtaining the advantages of a long coiled
spiral spring in a different way for shutters where the construction does not
lend itself to the spring being conveniently enclosed in the roller and where
the volute form of spring would be unsatisfactory.

page_text: The invention will be fully described with reference to the accompanying
drawings.
Fig. 1, is a front elevation of shutter showing one arrangement of the
invention.
Fig. 2, is an end view of shutter showing the releasing mechanism for the
blind.
Fig. 3, is a front elevation showing a modified arrangement of the invention.
Fig. 4, is an end elevation of shutter showing another modified arrangement.
Fig. 5, is an end elevation showing another modification.
Fig. 6, is another modification of arrangement of the spring.
Fig. 7, is an end elevation of tension adjusting device for the actuating spring.
Fig. 8, is a side elevation of Fig. 7.
The blind is driven by a closely coiled spiral spring of very small diameter
and considerable length which gives motion to the blind by reason of the spring
exerting a pull in the direction of its length after having been elongated by the
action of winding the blind upon the opposite roller to that to which the spring
is attached.
The blind A is mounted upon or attached to two rollers B & C the rotation
of either of which in one direction winds the blind A upon it drawing it at the
same time off the other.
In Fig. 1a long spiral spring D is attached at one end to the shutter case E
and at the other end is attached to a small worm or pulley on the spindle of
the roller B. The spring I wraps round the worm or pulley b in the reverse
direction to that in which the blind A wraps round the roller B consequently as
the blind A is unwound the spring is wound up and thereby elongated and vice
versa. A pulley c is placed on the end of the spindle of the roller C round which
a cord is wound in the reverse direction to that in which the blind is wound
upon the roller C. The blind is wound up upon the roller C by the pulling of
the cord F and unwinding of it from its pulleye the same action drawing the blind
off the roller B and causing the roller and worm or pulley b to rotate thereby
winding up a length of the spring D on the worm or pulley 6 elongating it and
putting it in tension.
b
On the release of the blind A the tension of the spring actuates the roller B
and with it the blind A.
The arrangement shown in Fig. 3 is very similar to that shown in Fig. 1
the spring being connected to the pulley b on the end of the roller B by a
cord which is wound upon the pulley b₁ to elongate and put tension on the
spring.
In Fig. 4 the long straight spring D is attached to a wheel or disc G gearing
with a pinion H on the end of the roller B. The rotation of the roller rotates the
pinion H and that rotates the wheel G half a revolution drawing the spring 1
upwards and putting it in tension. On the release of the blind roller the spring
draws the wheel G back to the position shown rotating the roller again in the
reverse direction and thereby actuating the blind for exposure.
In Fig. 5, the long straight spring D is attached to a sliding rack K gearing
with the wheels H & L on the top and bottom rollers. The movement of the
1oller in one direction or of the rack Kitself elongates the spring D and the
release of the roller permits the action of the spring to move the rack back in
the reverse direction and thereby rotate the roller. The rack K preferably
gears also with a pinion L on the other roller.
The tension of the spring may be adjusted by means of a pin M fitting into
holes m m¹ m² into either of which the pin M may be placed as in Figs. 4 & 5
or by a rack n' as in Fig. 6. Or the tension may be adjusted by a slide N to
which the spring D is attached and moved backwards or forwards by a screw n
as in Figs. 7 & 8.
In Fig. 6, the long spring D is passed round a pulley to increase its length.

page_text: The spring actuated roller B is held against the tension of the long straight
spring when set and released for exposure by a mechanism of ordinary con-
struction such for example as shown in Fig. 2, comprising a disc O with stop
pins o o¹. A stop lever P and a pneumatic bulb p for raising the lever P out
of contact with the pin o.
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. A photographic shutter constructed with a long thin spiral spring acting
in the direction of its length to actuate the blind roller in which one end of
spring is attached to or connected direct with the blind roller and the other
end is fixed or adjustable substantially as and for the purpose described.
2. In a photographic shutter the combination with the blind A and rollers B
and C upon which the blind A is wound of a long straight spiral spring attached
at one end to the case or a movable block and at the other end to the roller
which is elongated by the rotation of the roller and springs back when the roller
is released substantially as described.
3. A photographic shutter with a long thin spiral spring acting in the direc-
tion of its length to actuate the blind roller constructed and arranged in com.
bination substantially as described with reference to either of the figs. of the
drawings.
Dated this 21st day of February 1900.
WM. P. THOMPSON & Co.,
6, Bank Street, Manchester, Patent Agents.