IMPROVEMENTS IN OR RELATING TO VENETIAN BLINDS
Year: 1884

page_text: 13
I ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex
Engineer do hereby declare the nature of this Invention for "IMPROVEMENTS IN
OR RELATING TO VENETIAN BLINDS and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
This construction of autodynamic blinds is exclusively based on the principle of
counterweights. It consists of a principal bar or lath a of oak upon which are
placed two pulleys A and B each mounted on a support C and D, the blind also has
two double supports E and F each carrying two pulley's (G.H. I. J.) At the end
of the double supports are fixed the axles K and L which support the principal
lath or bar.
These shafts are each furnished with a ring M and N which rings are placed into
the walls or upon the uprights hereinafter mentioned and in which pivot the
axles K and L. One of the double supports E is moveable and slides in the lath
so as to allow this latter to pass into the window embrasure so that it can be more
readily mounted. As soon as the principal lath is put into the proper place, the
support E is caused to slide in the principal lath provided for this purpose with an
elongated hole and a bolt. The axle L being inserted in the ring N the axle K is
inserted in the ring M. and the bolt O is tightened; the principal lath and with it
the whole blind being thus put into the proper place.
Over each pulley A and B passes a chain say of galvanized iron, indicated by a
dotted line. One end of each chain is fixed to the bottom bar or lath passing it
therethrough the chains then pass through each lath of the blind. Slots being
provided for this purpose. They also pass through the principal luth and then
over the pulleys A and B extending over the pulleys G and I on the double
supports E and F. At this point each chain is attached to a counterweight say of
lead; placed one P at the right hand side the other Q at the left hand.
The weight of these two counterweights together exceeds that of the laths of
the blind and of the chain carrying the same by about a kilogram so that the
weight of the counterweights is in direct proportion to that of the total number
of laths in the blind and of the chain plus about a kilogram to allow for friction,
Price 61

page_text: Under these conditions the power would bear the same proportion to the load as
the load to the power if the load to be pulled by the counterweights were the same
throughout the path in which the laths rise and descend this is however not the
case. In fact by reason of the above described combination when the counter-
weights are at the top of the casement the laths of the blind are at the bottom and
vice versa. But in the descent the latter successively become detached in the
degree of their grouping and according to the divisions of the chain which supports
the laths and the weight diminishes the more, the more laths are on the way.
Ultimately one arrives at the bottom its weight is almost nil and the counterweights
are at the top in full force. The same takes place in the upward movement.
laths gradually become grouped amongst themselves starting from the bottom they
arrive at the top all heaped together and the equilibrium is re-established.
Consequently when the laths of the blind are lowered the equilibrium ceases as
the counterweight always remains the same and it is re-established automatically
when they are raised.
The
The raising therefore takes place quite naturally by the force of the counter-
weights which at their starting meet with scarcely any resistance. At their
descent however the laths have to be counterprised by some power as the number
of laths is diminished (and consequently their weight in proportion as they arrive
at the bottom. This power is designed to be exerted by slight traction exerted by
hand by means of a second chain R indicated by a dotted line and also attached to
a counterweight I.
This chain passes over pulley II of the double support F crosses the main lath
obliquely so as to be clear of the supports C and D and it engages in a slot S of the
principal lath in passing over the pulley R' placed on the double support F and is
then connected with another chain likewise fixed to counterweight and passing.
over pulley J of the double support F. Thus fixed these chains form a single chain
passing in the notch or slots of the principal lath and extending to the point U
where a ring retains the same so as to prevent the chains trailing on the ground
when the blind is lowered. To the same ring is fixed a hook which holds the
weights suspended at the top whilst the blind is stretched from top to bottom.
When the blind is to be raised again the chain is unlocked and the laths of the
blind rise as it were of their own accord and for this reason this blind is called
"autodynamic.”
All the supports for the pulleys are provided with straps say of iron which
prevent the chains being thrown out of the grooves of their pulleys by every slight
shock Bay by the reversing of the laths for the purpose of admitting more or less
light whereby the said supports are sometimes brought into a vertical, sometimes
into an oblique and sometimes into a horizontal position accordings
as to whether
the principal lath is set so as to admit more or less light. The mechanism for
varying the admission of light is operated by a toothed segment V fixed on the
underside of the principal lath below the double support F.
It is set in motion by an endless screw X supported by a forked support Y made
in one piece with the ring M. The endless screw is operated by means of a chain
or cord, or a cable passing over pulley G at the point M of the embrasure and
transmits its movement to another pulley II fixed on the axis of the endless screw.
The counterweights are hidden at each side of the embrasure behind panels O¹ F¹
of wood. In each panel is made a slot according to the size of the counter-
weights P. Q. Besides these arrangements I have adopted another which is not
less important for preventing the blind beating against the panes during high
winds. This apparatus consists of a parallellogramm fixed in the panals at the sides
of the window embrasure. Two iron rods B¹. C¹ pivot on studs F' placed at the
centre of each panel and one below. Midway of the height of the two wooden
uprights connected with each of the rods B¹ and C¹ there is a toothed segment that
can be operated by hand and serves to set the parallellogramm as desired till it is in
such a position as to ensure the rigidity of the laths.

page_text: All the movements of the blind can be effected from within the room without
requiring the window to be opened. It is sufficient to pierce the upright of the
window frame with a small hole following the inclination of the traction chain,
this hole is fitted with a small roller to avoid all friction of the chain which is
passed through the opening a similar arrangement is made to regulate the amount
of light to be admitted..
Instead of rising the parallellogramm fixed on the panels at the sides of the
embrasures of the window "broken" or hinged panels such as shown in 6. 7 and 8
may be used.
Having now described my said Invention and the manner of performing the
same I wish it to be understood that what I claim and desire to protect is:-
1. The combination with a venetian blind of the counterweights P & Q,
substantially as and for the purpose specified.
2. The combination with a venetian blind of the segment V worm X and means
for operating the same as a means of adjusting the position of the laths
substantially as described and illustrated.
3. The combination with a venetian blind of the parallellogramm of bars at each
end of the laths whereby the "beating" of the blind is prevented as
described.
4. For preventing the "beating" of the blind the "broken" or 'hinged boards or
panels embracing the laths substantially as set forth and illustrated in the
annexed Drawing.
A
.
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