IMPROVED APPLIANCES FOR ADJUSTING AND REGULATING THE WORKING OF INSTANTANEOUS PHOTOGRAPAIC SHUTTERS
Year: 1881

page_text: LETTERS PATENT to Charles Sands, of 20, Cranbourn Street, Leicester Square,
in the County of Middlesex, for an Invention of "IMPROVED APPLIANCES
FOR ADJUSTING AND REGULATING THE WORKING OF INSTANTANEOUS
PHOTOGRAPAIC SHUTTERS."
PROVISIONAL SPECIFICATION left by the said Charles Sands at the
Office of the Commissioners of Patents on the 25th June 1881.
CHARLES SANDS, of 20, Cranbourn Street, Leicester Square, in the County of
Middlesex, "IMPROVED APPLIANCES FOR ADJUSTING AND REGULATING THE
WORKING OF INSTANTANEOUS PHOTOGRAPHIC SHUTTERS."
My Invention relates to improvements connected with the instantaneous
photographic shutter communicated to the Manchester Photographic Society by
the late Michael Noton and described under the title of "An Exposing Valve for
Rapid Plates," in the British Journal of Photography of November 21st 1879,
pages 555 and 556, and the said improvements have for object to afford a ready
and reliable means of regulating the strength of the spring by which the shutter
is worked, whereby the length of time during which the shutter will be open, or
in other words the duration of the exposure, can be increased or diminished and
accurately predetermined and denoted according to requirements.
The improvements have also for their object to enable the shutter to be fixed in
any position or kept open for any length of time, and when used as a diaphragm
or stop between the lenses to denote the size of the aperture and the corresponding
length of exposure required. I do not however claim as of my Invention the
placing the shutter between the lenses, nor its use as a diaphragm or stop.
The shutter, like that described in the publication before referred to, consists of
two metal plates, each having a diamond shaped aperture, the said plates working
over one another and being capable of occupying either of two extreme positions in

page_text: which their apertures do not coincide, and the shutter is consequently closed, and
in passing from the one to the other of which positions the apertures coincide and
the shutter is open for a greater or less length of time, according to the speed at
which the plates are moved. The said plates are operated through links by crank
pins at opposite sides of a rotating crank disc, so that the plates are moved in
opposite directions, this disc being actuated by a spring coiled upon its axis. So
far the shutter is similar to that before referred to.
My Invention consists in the means of adjusting the spring for the purpose of
regulating and denoting the duration of the exposure, said means consisting in
enclosing the spring in a drum or box provided with ratchet teeth engaging a pawl
upon the frame, and with a pointer and scale annexed to denote the extent to
which the spring is wound up, and consequently the length of time occupied by
the apertures in passing one another. The shutter is set by means of a small
knob and fastened to the crank plate, which is revolved half a turn and held by a
small spring trigger engaging a notch in the edge of the crank plate. The small
knob is adjustable, that is to say, it may be turned to any less extent to fix the
shutter in any position and keep it open for any length of time, the said knob
serving also as an index in connection with an adjacent scale to denote the size of
the aperture and the corresponding length of exposure required.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent and of
an Order of the Lord Chancellor filed by the said Charles Sands in the Great
Seal Patent Office on the 11th April 1882.
CHARLES SANDS, of 20, Cranbourn Street, Leicester Square, in the County of
Middlesex. "IMPROVED APPLIANCES FOR ADJUSTING AND REGULATING THE
WORKING OF INSTANTANEOUS PHOTOGRAPHIC SHUTTERS."
My Invention relates to improvements connected with the instantaneous
photographic shutter, communicated to the Manchester Photographic Society by
the late Michael Noton, and described under the title of "An Exposing Valve for
Rapid Plates," in the British Journal of Photography of November 21st 1879,
pages 555 and 556, and the said improvements have for object to afford a ready
and reliable means of regulating the strength of the spring by which the shutter
is worked, whereby the length of time during which the shutter will be open, or
in other words the duration of the exposure, can be increased or diminished and
accurately predetermined and denoted according to requirements.
The improvements have also for their object to enable the shutter to be fixed in
any position or kept open for any length of time, and when used as a diaphragm
or stop between the lenses to denote the size of the aperture and the corresponding
length of exposure required. I do not however claim the exclusive right of placing
the shutter between the lenses, nor its use as a diaphragm or stop.
The shutter, like that described in the publication before referred to, consists of
two metal plates, each having an aperture, the said plates working over one
another, and being capable of occupying either of two extreme positions, in which
their apertures do not coincide, and the shutter is consequently closed, and in
passing from the one to the other of which positions the apertures coincide, and
the shutter is open for a greater or less length of time, according to the speed at
which the plates are moved. The said plates are operated through links by crank
pins at opposite sides of a rotating crank disc, so that the plates are moved in
opposite directions, this disc being actuated by a spring coiled upon its axis. So
far the shutter is similar to that before referred to, except that the apertures in
the plates, although generally diamond shaped, may be varied in shape according
to circumstances.
My Invention consists in the means of accurately adjusting the spring for the
purpose of regulating and denoting the duration of the exposure, said means
consisting in enclosing the spring in a drum or box provided with ratchet teeth
engaging a pawl upon the frame, and with a pointer and scale annexed to denote
the extent to which the spring is wound up, and consequently the length of time
occupied by the apertures in passing one another. The shutter is set by means of
a small knob fastened to the crank plate, which is revolved half a turn and held
by a small spring trigger engaging a notch in the edge of the crank plate. The
crank plate may be turned to any less extent to fix the shutter in any position and
keep it open for any length of time, the said knob serving also as an index in
connection with an adjacent scale to denote the size of the aperture in different
positions of the shutter, which cannot be conveniently ascertained except by means
of such a scale when the shutter is used as a diaphragm or stop, said scale also
indicating the corresponding length of exposure required.

page_text: section; Figure 2 is a similar view of the shutter after exposure or before being
set; Figure 3 is a face view, showing the shutter fixed full open for ordinary long
exposures; Figure 4 is a longitudinal vertical section through the axis of the crank
disc; Figure 5 shows the crank disc separately; Figure 6 is a diagram showing
the corresponding positions of the plates and of the index and scale when the
shutter is used as a diaphragm, the figures of the scale denoting the exact relative
sizes of the aperture in the different positions of the plates, and the relative times
of exposure for the different sizes of aperture. A, B, are the two plates of the
Noton shutter, each formed with a diamond shaped aperture a, b, and fitted to
slide between guides in a wooden casing C, to the front and back of which may be
fixed the adapters to carry the lenses when the shutter is intended to work between
the lenses of a double combination, but the shutter may also be placed in front of
or behind the lenses. Figures 1 and 2 illustrate the two extreme positions of these
plates, in both of which the shutter is closed; and Figure 3 illustrates the mid
position, in which the apertures a, b, coincide with one another for a greater or less
length of time as the plates pass from the position, Figure 1, to that of Figure 2.
D are the links by which the plates A, B, are connected to the crank disc E, the
links being pivoted to the crank pins d at opposite sides of the disc E, and to
pins on the plates A, B. The crank disc E is fixed on a central stud or spindle c,
and it has a semicircular slot F (Figure 5) in it, through which a stud screwed into
the casing passes to limit its rotation, the disc being enclosed and turning between
the front and back plates of a metal casing G. H is a volute spring spring contained
within a box or drum I, and coiled about the end of the spindle e, which projects
into the said box or drum through a hole in the bottom thereof, the inner end of
the spring being hooked on to the spindle, and the outer end to the side of the
box I. This box I is fitted to turn loosely about the spindle in an aperture on the
front plate of the casing G, as shown in Figure 4, and is enclosed by a screw cap I'
secured by a set screw, and having preferably a milled rim or edge by which the
box or drum may be readily turned to wind up the spring. K is a circle of ratchet
teeth around the box I, and is a spring pawl engaging therewith to retain the
spring after being wound up to any desired tension. Instead of ratchet and pawl
any equivalent mechanical device holding the drum accurately in any desired
position may be used, avoiding mere friction between the parts as a means of
holding it, this not being reliable. L is a circular scale engraved or marked upon
the casing G, divided and figured to denote in connection with a pointer upon the
drum the extent to which the spring is wound by turning the drum until the
pointer is directed towards the different divisions of the scale, and the length of
exposure at each corresponding speed. M is a spring detent or trigger mounted in
the side of the casing G, and engaging with notches in the edge of the disc E, one e¹
to hold the shutter in the set position, Figure 1, and one e², to hold it in the open
position, Figure 3. There may be other notches to hold the disc in different
positions if desired. N is a thumb knob fixed to the disc E, and passing through
a semicircular slot n in the casing, by which the disc E is turned to set the shutter,
as shown in Figure 1. This knob carries an index moving over a scale P marked
alongside the slot n, and so divided and figured as to indicate different positions of
the shutter in which the areas of the aperture increase or diminish according to any
desired rate of progression, the length of exposure required for each varying
accordingly. For example, the area of the aperture in positions Nos. 2, 4, 8 are
respectively a, a, and an 1/6th of the area in position No. 1, and the length
of exposure needed is 2, 4, or 8 times as long, and so on. To fix the shutter in any of
these positions the spring H is either unwound by releasing the pawl from the
ratchet, or the disc E has notches for the detent M to engage in. In this case the
scale would preferably be in the dotted position P'.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as my Invention to be protected by the
hereinbefore in part recited Letters Patent is,-
1st. The combination with an instantaneous photographic shutter, such as herein

page_text: described, of the means of accurately adjusting the strength of the spring for the
purpose of varying the length of exposure, substantially as herein described and
shown in the Drawings.
2nd. The combination with an instantaneous photographic shutter, such as herein
described, of the said means of accurately adjusting the strength of the spring, and
of the scale and index for denoting the length of exposure given for each adjust-
ment of the spring, substantially as described and shown in the Drawings.
3rd. The combination with an instantaneous photographic shutter, such as herein
described, of the index and scale for denoting the relative sizes of the aperture and
the corresponding relative times of exposure required when the shutter is used as a
diaphragm or stop, substantially as shown and described.
4th. In an instantaneous photographic shutter the construction, combination, and
arrangement of the parts, viz., the slotted disc and its thumb knob, the slotted
casing enclosing said disc, the spring trigger and the spring drum exterior to said
casing, substantially as shown and described.
In witness whereof, I, the said Charles Sands, have hereunto set my hand
and seal, this Tenth day of April, A.D. 1882.
CHARLES SANDS.
(L.S.)