Note: Descriptions are shown in the official language in which they were submitted.
CA 02467357 2004-05-17
BALANCED TILT MECHANISM FOR A COVERING FOR AN
ARCHITECTURAL OPENING
CROSS-REFERENCE TO RELATED APPLICATION
This application is a non-provisional application which claims priority to
U.S.
provisional application No. 60/381,587, filed 17 May 2002, which application
is
incorporated by reference herewith in its entirety
BACKGROUND OF THE INVENTION
Field of the Invention
'The present invention relates generally to tilt mechanisms for operating
retractable coverings for architectural openings and more particularly to a
counterbalanced system to facilitate the ease of operation:
Descrintion~of the Relevant Art
This invention relates generally to mechanisms for tilting the slats or vanes
of
a covering for an architectural opening, and more specifically to a
couziterbalanced
mechanism for low effort tilting of the slats of a horizontal blind covering.
Conventional Venetian-style blinds typically comprise a fined head rail that
is
mounted to a window frame or ether architectural openings through mounting
brackets located at the ends of the head rail. To tilt the hotizontai slats of
the
conventional style Venetian blind, a wand hanging from the head rail is
rotated. The
wand is connected to a tilt mechanism located within the head rail. Rotation
of the
wand turns one or more gears of the tilt mechanism that in turn rotate a tilt
rod that
extends generally along the length of and is contained within the head rail.
At two or more locations along the head rail the tilt rod is operatively
connected to the ends of a ladder tape. The ladder tape typically comprises
two
vertical cords that extend downwardly from the head rail: one in front of the
slats; and
one behind the slats. The lower ends of the ladder tape are typically
connected to a
weighted foot rail. The vertical cords of each ladder tape are connected by
cross rungs
that also act to cradle and support associated slats of the blind. When the
tilt rod is
rotated, one of the vertical cords of each ladder tape is pulled upwardly into
the head
rail while the other vertical cord is pulled downwardly by the weight of the
foot rail as
CA 02467357 2004-05-17
additional cord is fed from the head rail. Accordingly, the cross rungs are
pivoted
between horizontal and generally vertical orientations, thereby tilting the
slats they are
supporting.
The conventional tilt mechanism is typically limited to use in Venetian-style
blinds having a stationary head rail, which can contain and support the tilt
mechanism
including the longitudinally extending tilt rod. Fixed head rails are
generally not
considered to be aesthetically pleasing. Accordingly, head rails are often
covered with
valances or in other situations stationary slats are adhesively secured to the
head rail
to give the impression that the slats of the blind assembly extend the entire
length of
the blind.
Although conventional tilt mechanisms are generally very effective, friction
in
the mechanisms-can require a significant amount of effort to be expended by
the user
to tilt the slats. Further, to tilt the slats from one closed position all the
way to the
opposite clo$ed position a significant number of toms of the tilt wand are
often
required (typically 6 or more). A certain level of hand dexterity is required
to operate
the~small diameter wand (larger diameter wands would distract from the
aesthetics of
the blinds) and accordingly, certain persons, such as the elderly, may find
the
conventional tzlt mechanisms difficult to operate.
BRIEF SUMMARY OF THE INVENTION
A balanced mechanism for the tilting of horizontal blinds incorporating a
tiltable head rail along with a blind assembly incorporating the balanced tilt
mechanism are described. The balanced tilt mechanism permits the slats Cor
vanes) of
the horizontal blinds to be pivoted in either clockwise or counterclockwise
directions
with minimal effort by gently lifting or pulling on a weighted tassel hanging
from the
end of a tilt actuator cord. '
BRIEF DESCRIPTION OF THE DRAWINGS .
Figure 1 is an isometric front view of a horizontal blind assembly
incorporating a balanced tilt mechanism according to one embodiment of the
present
invention.
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Figure 2 is a partial front view of the horizontal blind assembly of Figure 1
illustrating the weighted tassel on the end of the tilt actuating cord.
Figure 3 is a cross sectional view of the horizontally blind assembly of
Figure
1 taken along line 3-3 of Figure 2.
Figures 4-6 are cross sectional views of the horizontally extending blind
assembly similar to the Figure 3 view illustrating the slats (or vanes) in
various tilt
positions.
Figure 7 is a top view of the balanced tilt mechanism taken along line 7-7 of
Figure 2 illustraring the positioning of the tilt actuating cord on the
tapered bobbin
when the vanes are in the fully open tilt position as illustrated in Figure 3.
Figure 8 is a top view of the balanced tilt mechanism taken along line 7-7 of
Figure 2 illustrating the positioning of the tilt actuating cord on the
tapered bobbin
when the vanes are in a second closed tilt position as illustrated in Figure
6.
Figure 9 is a top view of the balanced tilt mechanism taken along line 7-7 of
Figure 2 illustrating the positioning of the tilt actuating cord on the
tapered bobbin
when the vanes are in a first closed-tilt position as illustrated in Figure 5.
Figure 10 is a cross sectional view of the balanced tilt mechanism taken along
line 10-10 of Figure 7.
Figure 11 is a cross sectional view of the balanced tilt mechanism taken along
line 11-11 of Figure 7.
Figure 12 is a cross sectional view of tla; balanced tilt mechanism taken
along
line 12-12 of Figure.7.
Figures 13A-13C are partial cross sectional views of the balanced tilt
mechanism taken along line 13A-13A of Figure 7 illustrating the positioning of
the
tilt actuating cord relative to the bobbin when the slats are in three
different tilt
positions: the fully open position; the second closed position; and the first
closed
position respectively:
Figures 14A-14C are partial cross sectional views of the balanced tilt
mechanism taken along line 14A-14A of Figure 7 illustrating the positioning of
the
constant tension-type spring when the slats are in three different tilt
positions: the
fully open position; the second closed position; and the first closed position
respectively.
CA 02467357 2004-05-17
Figure 1 S is a fragmentary diagrammatic elevation of a second embodiment of
the balanced tilt mechanism
Figure 16 is a section taken along line 16-lb of Figure 15 wherein the
headrail
for the system is shown in dashed lines.
Figure 17 is a section similar to Figure 16 with the component parts in a
different position.
Figure 18 is an exploded isometric showing the component parts of the
embodiment of the invention shown in Figure 15.
Figure 19 is a fragmentary exploded isometric showing the balanced tilt
mechanism of the embodiment of Figure 18 removed from the end of the headrail
and
with a cord ladder and suspended slats shown with the balanced tilt mechanism.
Figure 20 is an enlarged fragmentary section taken along line 20-20 of Figure
15.
Figure 21 is a section taken along line 21-21 of Figure 20.
Figure 22 is a section taken along line 22-22 of Figure 20.
Figure 23 is a fragmentary section taken along line 23-23 of Figure 20.
Figure 24 is a fragmentary section taken along line 24-24 of Figure 23.
Figure 25 is a section similar to Figure 23 showing the actuator card at a
different location on the bobbin.
Figure 26 is a section taken along line 26-26 of Figure 25.
Fignre 27 is a section taken along line 27-27 of Figure 20.
Figure 28 is a section taken along line 28-28 of Figure 20.
DETAILED DESCRIPTION OF THE INVENTION
A balanced tilt mechanism and a blind assembly incorporating the 'balanced
tilt mechanism are described. In a preferred embodiment of the balanced tilt
mechanism, a weight hanging off the end of a rift actuator cord applying a
downwardly biasing force is balancxd against a spring located within the head
rail that
applies a contravening upwardly biasing force to the, tilt actuating cord. The
card is
wrapped around a bobbin that is operatively coupled' to a tiItable head rail
through one
or more gears to permit the pivoting of the head rail about rotational shafts
associated
with mounting brackets, Operationally, the balance is upset by gently pushing
or
pulling up or down on the tilt actuator card, thereby causing the cord to
retract or
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extend and the head rail to tilt accordingly. It is to be appreciated that
because the
mechanism is balanced very little effort is required to tilt the blinds,
The Blind Assembly
Referring to Figures 1-6, one embodiment of a window blind assembly 100
incorporating the balanced tilt mechanism is illustrated. While the present
invention.
will be described for use as a window blind, it will be appreciated that a
substantially
similar blind assembly could be utilized with any architectural opening, such
as
doorways, archways and the like. The blind assembly 100~comprises: (i) a
horizontally-extending slat-shaped rigid head rail 105 that is pivotally
coupled to a
window frame 110 by a pair of mounting brackets 115; (ii) a horizontally-
extending
somewhat rigid lower slat 120 coupled to the top slat by a plurality of lift
cords (not
shown) and ladder tapes 125; (iii) a plurality of horizontal slats 130
disposed between
the head rail and the lower slat and coupled thereto by the ladder tapes; {iv)
a lift
actuator cord 135 for lifting and lowering the stats; and (v) a tilt actuator
cord 140
including a weighted end tassel 145.
The illustrated blind assembly utilizes somewhat airfoil-shaped hollow slats,
bottom slat and head rail. The construction of the. slats and the blind
assembly is
described in greater detail in U.S. Patent Application Serial No. 101197,674
filed
I6 July 2002, and PCT Application No. PCTIUS02100225 filed 16 July 2002, which
are commonly owned by the Assignee of the present invention, and are hereby
incorporated by reference in their entirety. Alternative configuration blind
assemblies
are anticipated as the slats can be in any suitable shape and fabricated from
any
suitable material. For instance, slats fabricated from plastic, fabric, metal
and wood
are contemplated. Further, the head rail can be of any number of shape
configurations
that are similar to or different from the associated slats. The lift mechanism
can be of
any suitable conventional type or it can be similar to the lift mechanisms
described in
the patents incorporated by reference and, as such, the lift mechanism will
not be
described in any greater detail herein.
The ladder tapes 125 illustrated in Figures 1-3 typically comprise front and
rear vertical cords that extend vertically across the front edges and rear
edges
respectively of the slats. Cross rungs (nonspecifically illustrated) span
between each
set of vertical cords at vertically-spaced locations to support and cradle the
slats 130.
In the preferred embodiment, the top end of eachwertical cord is secured to
one of the
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CA 02467357 2004-05-17
front edge and the rear edge of the head rail (as illustrated in Figure 7),
wherein the
tops of the vertical cords are threaded through holes in the edges of the head
rail and
secured therein by a knot or an adhesive bead 150. Accordingly, when the head
rail is
tilted clockwise as shown in Figure 4, the front vertical cord of each ladder
tape 125 is
S lowered and the rear vertical cord of each (adder tape is raised, thereby
causing the
cross rungs to pivot clockwise along with the slats cradled in the crass
rungs.
Conversely, when the head rail is tilted counterclockwise as shown in Figure
6, the
front vertical cord of each ladder tape 125 is raised and the rear vertical
cord of each
ladder tape is towered, thereby causing the~cross rungs to pivot
counterclockwise
along with the slats cradled in the cross rungs.
Referring to Figure 3, the blind assembly is illustrated with the slats in the
fully open position. In this position the slats, head rail and foot rail are
orientated
substantially horizontally in their widthwise direction. The weighted tassel
145
attached to the end of the tilt actuator cord 140 is located at an
intermediate vertical
I 5 position that is easily reached by a user to move the slats into either a
first or a second
closed position.
As illustrated by the arrows in Figures 4-6, by pulling the tassel 145 andJor
associated tilt actuator cord 140 upwardly or downwardly, the head rail pivots
about
the mounting brackets 115 causing the associated slats 130 to pivot as well.
By
pulling downwardIy with a small force on the tassel 145 as shown in Figure 4,
the
effective downwardly acting force is increased to an amount greater than an
upwardly
acting force applied by the contravening spring 218 (as best shown in Figures
14A-C
described in detail below). Accordingly, the head rail and the slats pivot in
a
clockwise direction unfit reaching a first closed position. T'Ite first closed
position is
illustrated in Figure 5. Conversely, by gently pulling or pushing upwardly on
the
tassel 145 or the Lift actuator card 140, the effective downwardly acting
force as
applied by the tassel weight is decreased to an amount below the upwardly
acting
force applied by the contravening spring. Accordingly, the head rail and the
slats
pivot in a counterclockwise direction until reaching a second closed position
as
illustrated in Figure 6.
It is to be appreciated the amount of force that must be applied by the user
is
very small comprising only the amount of force necessary to overcome any
rotational
friction inherent in the tilt mechanism, The amount of friction is largely
dependant on
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CA 02467357 2004-05-17
the design of the mechanism, but a small amount of friction is desirable and
necessary
to prevent the slats from tilting to and fro when encountering even the
smallest
external forces, such as might be the result of breezes passing through an
open
window for example. It is contemplated that in alternative embodiments, a
mechanism may be provided, such as a clamp arrangement around one or more of
the
pivoting shafts of either the tilt mechanism or the head rail to allow
adjustment of the
level of friction in the system.
The Balanced Titt Mechanism
Referring to Figures 7-14C, the tilt mechanism 200 is illustrated. In
general, the balanced tilt mechanism comprises: (i) the tilt actuator cord
140; (ii) the
weighted tassel 145; {iii) a bobbin/spring assembly 210'including a tapered
bobbin
212 rotatably mounted within the head rail by a bobbin shaft 214, a bobbin
spur gear
216, and a constant tension-type spring 218; (iv) a spur gear assembly 24.0
including a
large spur gear 242 and a small spur gear 244 attached by a rotating shaft
246; and (v)
a mounting bracket attachment assembly 250 including a rotationally fixed spur
gear
252, and a head rail shaft 254 about which the head rail pivots.
The bobbinlspring assembly 210 is best illustrated in Figures 7-9 with
transverse cross sections of the tapered bobbin 212 provided in Figures 13A-C
and
14A-C. The primary component of the bobbin/spring assembly is the tapered
bobbin
212. The tapered bobbin acts to transfer the spring force from the spring 2i8
to the tilt
actuator cord 140 and to secure the tilt actuator cord to~the tilt mechanism.
The
tapered bobbin 212 is generally cylindrical with a tapered conical section and
is
adapted for rotation about a bobbin shaft 2I4 that extends through the tapered
bobbin's longitudinal axis. The tapered bobbin can be fabricated from any
number of
suitable materials including metals, plastics and composites, but in the
preferred
embodiment, the tapered bobbin is fabricated from an injection molded plastic.
The
bobbin shaft 214 that is typicatly fabricated from a metallic material is
press fit onto
the bobbin along the bobbin's longitudinal axis. Alternatively, the shaft may
be keyed
to the shaft or adhesively bonded to the shaft for unitary rotation therewith.
In an
alternative embodiment, the bobbin shaft can be integrally molded with the
bobbin.
The bobbin shaft is rotatably received at either end of the bobbin into slots
or
openings formed in the head rail 105. It is appreciated that as illustrated in
Figures 7-
9 that the tilt mechanism is supported in an end cap section 106 of the head
rail that is
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received in a longitudinally-extending typically extruded secrion 108 of the
head rail
105,
The tapered bobbinlbobbin shaft combination comprises several
sections along its longitudinal length including a spring section 220 at one
end of the
tapered bobbin 212. The spring wrap section 220 is essentially cylindrical and
is
bounded on both ends by first and second radial flanges 222 and 224. A
longitudinally-extending slot 226 (best illustrated in Figure 14A) is provided
through
the wall of the cylindrical spring section for securing a hooked end 228 ofthe
spring
218. As the slats are tilted in either direction during the operation of the
tilt
mechanism 200, the constant tension type spring 218 either wraps around the
spring
section 220 or unwinds from the spring section 220 and wraps around a post 230
provided in the head rail 105.
The tapered bobbin 212 also includes a tapered section 232 between
the second radial flange 224 and a third radial flange 234 wherein the wall of
the
bobbin is tapered from a first diameter proximate the second radial flange to
a second
smaller diameter proximate the third radial flange. The change in the diameter
around
which the cord is wrapped changes the bias on the bobbin caused.by the tassel
and
thereby compensates for changes in the biasing force provided by the spring
218
depending on the amount of the spring that is.wrapped around the spring
section 220.
The surface of the tapered section also includes a continuous groove 236 which
extends from one end of the section 232 to the other wrapping about the
suzface of the
tapered section multiple times. The groove is sized to. receive the tilt
actuator cord 140
therein to guide the cord as it is wound and unwound from the bobbin 212
during
tilting operations. Proximate the second flange 222, a hole 238 of sufficient
diameter
to receive the top end of the tilt actuator cord passes through the wall of
the tapered
section 232 at one end of the cominuous groove 236 (as best shown in Figure i
3C).
This hole is used to secure the tilt actuator cord to the bobbin by passing
the cord
through the hole and either knotting the end or affixing an adhesive bead I60
to the
end of the cord that cannot fit back through the hole.
Finally, the bobbin shaft 214 that passes through and is fixedly secured to
the
tapered bobbin 214 has a bobbin spur gear 216 located above the tapered
section 232
on the other side of the third flange 234. The bobbin spur gear 216 is fixedly
received
onto the bobbin shaft for unitary rotation therewith. The bobbin spur gear can
be
8.
CA 02467357 2004-05-17
keyed to the bobbin shaft, press fit onto the bobbin shaft, adhesively bonded
to the
shaft or affixed to the shaft by any suitat~le means. In an alternative
embodiment,
where the bobbin shag is integrally fabricated with the tapered bobbin; the
bobbin
spur gear can also be integrally molded with the tapered bobbin.
Referring to Figure 7 and Figures 14A-C, as mentioned above, one end of the
constant tension-type spring 218 is hooked within a slot 226 in the spring
section 220
of the bobbin 212. The other end of the spring is wrapped around the spring
post 230
provided in the head rail 105 to receive the spring. The spring is typically
fabricated
from spring steel and provides a generally continuous tension across the span
of the
spring between the portion of the spring wrapped around the spring section 220
and
the portion of the spring wrapped around the spring post 230 in the direction
of the
spring section as indicated by the arrows in Figures 14A-C. Accordingly, the
spring
applies a clockwise bias to the tapered bobbin 212.
As successive layers of spring 218 are wrapped around the spring section 220,
the effective counterclockwise rotational moment applied to the tapered bobbin
212
from the spring increases since the distance from the longitudinal axis to the
biasing
portion of the spring increases and the force applied by the spring remains
constant
(the rotational moment is equal to the distance from the longitudinal axis to
the
location where the load is being applied times the force being applied). It is
to~be
appreciated that in order for the bobbin to remain stationary when the tilt
mechanism
is not being operated the counterclockwise rotational moment applied by the
weighted
tassel 145 acting through the tilt actuator cord 140 must be the same as the
contravening rotational moment applied by the spring. As the clockwise
rotational
moment increases, the counterclockwise rotational. moment must also increase.
The
tapered section 232 of the tapered bobbin causes the counterclockwise
rotational
moment to change in concert with the counterclockwise rotational moment.
For instance when the spring is wound its maximum amount around the spring
section 220 of the bobbin 212 as shown in Figure 14C, the tilt actuator cord
will be
completely unwound from the tapered section and be located at the largest
diameter
portion of the tapered section as shown in Figure 9. When the spring and the
tilt
actuator cord are in these positions on the tapered bobbin, the vanes will be
in their
first closed position as shown in Figure 5.
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Conversely, when the spring is wound its minimum amount around the spring
section 220 of the bobbin 212 as shown in Figure t 4B, the tilt actuator cord
140 will
be wound around the tapered section 232 its maximum amount and the portion of
the
cord coming off of the tapered section will be located at the smallest
diameter portion
of the tapered section as shown in Figure 8. When the spring and the tilt
actuator cord
are in these positions on the tapered bobbin, the vanes will be in their
second closed
position as shown in Figure 6.
The spur gear assembly 240 and the mounting bracket assembly 250 are
provided to transfer the rotational movement of the tapered bobbin 212 during
a
tilting operation to pivotal movement of the head rail 105 and the associated
slats 130.
IS
The spur gear assembly 240 and the mounting bracket assembly 250 are best
illustrated in Figure 7-12. The spur gear assembly includes the spur gear
shaft 246
that is rotationally mounted to the head rail and has the large spur gear 242
affixed to
it at one end and the small spur gear 244 affixed to it at the other end. The
large spur
gear is meshed with the bobbin spur gear 2I6 (as best shown in Figure 12) such
that
clockwise rotation of the bobbin spur gear causes the large spur gear and the
entire
spur gear assembly to rotate counterclockwise. The various components of the
spur
gear assembly can be made out of a variety of suitable materials including
plastic,
metals and composites. Further, the spur gears can be joined to the spur gear
shaft in
any suitable manner including but not limited to press fitting, adhesive
bonding,
welding, brazing. and keyed fitment. AdditSOnally, in an alternative
embodiment, the
entire spur gear assembly can be injection molded as a single piece using a
suitable
reinforced or unreinforced plastic.
As best shown in Figures 7 and 11 the small spur gear 244 is meshed with the
fixed spur gear 252 of the mounting bracket assembly. The fixed spur gear is
secured
to the end of the head rail shaft 254 of the mounting bracket pad 256 that is
frxedly
secured to the mounting bracket 115. Accordingly, the frxed spur gear does not
rotate.
Rather the small spur gear 244 moves around the surface of the fixed spur gear
and
since the small spur gear, the spur gear assembly and the tapered bobbin
assembly are
all contained within and attached to the head rail,-the head rail also pivots
relative to
the fixed spur gear.
In the afore-described embodiment, the fixed spur gear 252 has an axial
opening that is keyed to a corresponding portion of the head rail shaft 254 as
is best
CA 02467357 2004-05-17
illustrated in Figure 1 i. The head rail shaft further includes a radial
flange 258 at its
end to hold the fixed spur gear in place and prevent it from sliding off the
end of the
head rail shaft. In this portion of the head rail shaft there are two opposing
slots 2G0 in
the walls of the shaft 254 allowing the remaining walls to resiliently flex
inwardly as
the fxed spur gear 252 is snapped into place. In alternative embodiments, the
gear
252 may be fixed to the head rail shaft in any suitable manner including
welding and
bonding.
As best shown in Figures 7 and 10, the end of the head rail 105 is pivotally
mounted to the mounting bracket assembly 250 at another portion of the head
rail
shaft 254. The head rail is free to pivot about the shaft but cannot slide
longitudinally
off the shaflt as prevented by the mounting bracket pad 256, which is
typically integral
with the shaft 254, on one side and the fixed spur gear 252 on the other side.
It is to be
appreciated that the head rail 105 is longitudinally secured to a modified
mounting
bracket assembly for pivotal movement on the other end of the head rail
although no
fixed spur gear is required.
In the this embodiment of the invention, the mounting bracket pad 256
includes a spring catch (not shown) molded therein or otherwise attached to
the pad.
The spring catch is designed to be received in a plurality of mounting holes
(not
shown) disposed in the mounting bracket 215 at spaced circular locations about
a
center point coincident with the longitudinal axis of the head rail shaft 254.
Accordingly when mounting the blinds to an opening, the mounting brackets 215
are
first positioned and secured to the frame 110 of the opening. Next, the tilt
mechanism
200 is activated to move the blinds into one of the closed positions
before'attaching
the mounting bracket pads 256 to the mounting bracket. Finally, the pads 25d
are
' aligned to the bracket with the head rail and slats substantially vertically
disposed in
their lateral direction and the pads are snapped into place.
It is to be appreciated that depending on the various sizes of the spur gears
21 G, 242, 244, and 252 utilized throughout the tilt mechanism 200, the amount
of
weighted tassel movement necessary to move the slats I30 from one closed
position
to another can be varied as would be obvious to one of ordinary skill in the
art. In the
preferred embodiment, the total travel of the tilt actuator cord 140 and the
associated
weighted tassel 145 is about 22 inches, although the gearing could be changed
to
reduce that travel especially when used with small shades that are not very
tall. To
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prevent the tilt actuator cord from over winding onto the tapered bobbin 212
when
pivoting the slats into the second closed position, the tilt actuator cord has
a adhesive
bead 155 attached to it that braces against the cord opening in the head rail
when the
cord slats are fully tilted and the cord is fully wound about the tapered
bobbin as
shown in Figure 8.
Operation of the Blind Assembly and The Balanced Tiit Mechanism
As described above and illusfirated in Figures 4-5, to pivot the shades from
the
fully open position to the first closed position, a user gently pulls on the
weighted
tassel 145 or the tilt actuator cord 140. The force only need be enough to
overcome
any friction built into the tilt mechanism. As illustrated in Figure 13A, when
the
tapered bobbin is rotated in a counterclockwise direction; causing additional
spring to
be unwound from the spring section 220 of the bobbin as illustrated in Figure
14C, it
increases the clockwise acting rotational moment applied to the bobbin by the
spring.
To maintaiwthe balance of forces, the tilt actuator cord moves along the
groove 236 to
I 5 a portion of the tapered section 232 having a greater diameter as shown in
Figure 9
' thus increasing the counterclockwise bias on the bobbin which is applied by
the tassel.
The counterclockwise mtation of the tapered bobbin 212 and the fixedly
attached
bobbin spur gear causes the spur gear assembly, which is meshed to the bobbin
spur
gear through the large spur gear 242, to rotate clockwise. The small spur gear
244,
which is meshed against the fixed spur gear 252, moves clockwise around the
fixed
spur gear. Since the spur gear assembly is attached to the head rail 105, the
head rail
pivots clockwise about the mounting bracket assembly 250 as the small spur
gear
moves around the fixed spur gear. The counterclockwise pivotal movement of the
head rail causes the front vertical cord of the ladder tape 12S to rise, the
rear veriicaI
cord to be lowered, and the slats to be tilted into the second closed position
as shown
in Figure 5.
The foregoing balanced tilt mechanism has been described in terms of use
with a blind assembly incorporating a tilting head rail. It is to be
appreciated that
elements of the balanced tilt mechanism can also be utilized iri a more
conventional
Venetian blind assembly with a fixed head rail. In such an application the
tapered
bobbin/spring assembly would be interfaced either directly or through one or
more
gears with a tilt rod that extends within the head rail. By either lifting or
pulling on the
weighted tassel the balance of forces would be upset and the tapered bobbin
and the
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CA 02467357 2004-05-17
tilt rod would rotate to effect the tilting of the blind assembly's slats. The
balanced tilt
mechanism could also be incorporated into other types of window coverings that
tilt
or pivot slats.
Additionally, many variations of the various components of the tilt mechanism
are contemplated. For instance, the type of spring utilized could be varied or
in
another embodiment the spring could be replaced with a second weight that
hangs
down the back side of the blind to counteract the weighted tassel. In other
embodiments, the various gears could be replaced as applicable by pulleys and
drive
belts. In other variations, the bobbin may not be tapered. The scope of the
invention is
not intended to be limited to the specific embodiment described herein,
rather, the
described embodiments are provided by way of example.
An alternative embodiment 260 to that described previously is illustrated in
Figs. 15-28. This alternative embodiment is quite similar to the previously
.described
embodiment so that like parts have been given like reference numerals with a
prime
' suffix.
The embodiment 260 of Figs. 15-28 includes a tilt mechanism 262 that
comprises (i) a tilt actuator cord 140 ; (ii) a weighted tassel 145 ; (iii) a
bobbinlspring
assembly 264 including a tapered bobbin 266 rotatably mounted within the
headrail
i05' by a bobbin shaft 214', a bobbin spur gear 216', a constant tension-type
spring
269; (iv) a spur gear assembly 240' including a large spur gear 242' and a
small spur
gear 244' attached by a rotating shaft 246 ; and (v) a mounting bracket
attachment
assembly 270 including a rotationally fixed spur gear 272, a mounting disc
274, and a
headrail shaft 276 about which the headrail pivots. The aforenoted tilt
mechanism
262 is mounted in a housing 278 having upper 278u and lower 2781 components,
which are releasably connected together to confine the working components in
predetermined positions for reliable operation of the tilt mechanism.
The housing 278 with the tilt mechanism components therein is adapted to be
inserted into the open end of the hollowtubular headrail l OS° of the
type previously
described and positively positioned contiguous with the end of the headrail in
any
suitable manner such as by friction, adhesive or the like. Further, the
housing and ilt
mechanism are operably and releasably mounted on a bracket 280 that is fixed
to the
framework (not shown) of an architectural opening so that the housing, tilt
13
CA 02467357 2004-05-17
mechanism, and associated headrait can be tilted relative to the bracket upon
operation of the tilt mechanism.
'The bobbinlspring assembly 264 is best illustrated in Figs. 18 and 20-28. The
primary component of the bobbin/spring.assernbly is the bobbin 266 which is
identical to the bobbin described in the previous embodiment except for the
manner in
which the constant tension spring 269 is secured to the bobbin. In this
embodiment of
the invention, the end of the constant tension spring has an aperture 284
punched
therethrough and as is best seen in-Figs. 18 and 28, the end of the~spring is
adapted to
be inserted into a slot 286 provided in the cylindrical spring wrap section
288 of the
bobbin 266 where the aperture is disposed around a transverse pin 290 formed
in the
interior of the .spring wrap section of the bobbin. .It will therefore be
appreciated by
reference to Fig. 28 that rotation of the bobbin causes the constant tension
spring to be
wrapped around or unwrapped from the spring wrap section depending upon the
direction of potation of the bobbin and its relative relationship to the
constant tension
spring.
The upper and lower housing components 278u and 2781 are complementary
but not identical. As probably best seen in Figs. 18 and 20, the lower section
has a
number of dividers, bearing seats.; and cradles for receiving various
component parts
of the tilt mechanism as will be described hereafter. Along an axis of the
housing 278
and transversely centered between opposite edges of the housing that
correspond with
apposite inner and outer edges 292 and 294 respectively of the headrail 105',
an
elongated generally semi-cylindrically shaped, relatively large cradle 296 is
provided
to rotatably receive the bobbin 266. Axially aligned with the cradle 296 along
an
inner end 297 of the housing is a first bearing seat 298 adapted to rotatably
support
the shaft 214' of the bobbin. Adjacent to the outer end of the cradle, so as
to be in
adjacent side-by-side relationship with the tapered conical body of the bobbin
when
the bobbin is seated in the cradle, an arcuate tapered notch 300 is formed to
guide the
actuator cord 140' as it is f~i to and off the bobbin as will be described in
more detail
later.
Adjacent to the inner end of the relatively large cradle 296, a second smaller
cradle 302 is formed that communicates laterally with the relatively large
cradle and
F
is adapted to seat the constant tension spring 269 in its rolled form such
that the end
14
CA 02467357 2004-05-17
of the spring having the aperture 284 therethrough can extend into the larger
cradle
where it isreleasably attached to the bobbin 266 as.described previously.
At the outer end of the larger cradle 296, a first transverse divider wall 304
is
formed having a second bearing seat 306 axially aligned with the bobbin 266
for
rotatably supporting the shaft 214' on which the bobbin spur gear 216' is
mounted.
Accordingly, between the seats at the inner and outer end of the large cradle,
the
bobbin can be rotatably mounted for free rotation while being confined within
the
cradle. - -
Parallel to the first divider wall 304 but spaced outwardly therefrom is a
second divider wall 308 having third 310 and fourth 312 bearing seats formed
in its
top edge with the third bearing seat 3I0 adapted to rotatably support an
intermediate
portion of the shaft 246' between the gear 242' and the gear 244'. The fourth
bearing
seat 3 i 2 is adapted to rotatably support the innermost end of the shaft for
the spur
gear 272. 'The outer wall 314 of the bottom~housing companent has fifth 316
and
sixth 318 bearing seats with the fifth bearing seat supporting the outer end
of the shaft
246' associated with the gears 242° and 244' while the sixth bearing
seat supports an
intermediate portion of a shaft 254 associated with the gear 272. The outer
end of the
shaft 272 has the mounting or support disc 274 secured thereon which will be
described in more detail later for releasably connecting the tilt mechanism to
the
mounting bracket 280.
As will be appreciated, a pocket 324 is deftned between the first 304 and
second 308 transverse divider wails for confining the spur gears 216' and 242'
while
still another pocket 322 is defined between the second divider wall 308 and
the outer
end wall 314 of the lower housing component 2781 for confining the gears 244'
and
272. There is just enough space between the divider walls and the end wall to
allow
the respective gears to rotate freely but to prevent them from tilting during
operation
of the tilt mechanism. Accordingly, the gears always remain in operative and
meshed
relationship as desired for dependable operation of the system.
Along the inner end wall 297 of the lower housing component 2781, a shelf
326 is provided with circular recesses 328 for rotatably receiving a pair of
pulleys 330
having vertically extending axles 332 with one end of the axles being
rotatably
received in a centered aperture 334 within the circular recesses. As probably
best
appreciated by reference to Fig. 20, the pulleys 330 are provided to guide
front and
15 .
CA 02467357 2004-05-17
rear lift cords 135' which extend through transverse slots 340 along the
lateral inner
and outer edges of the lower housing component. The lift cords could be part
of a
system of the type described in the aforementioned PCT application No.
PCT/US02/00225.
Along the outer lateral edge of the lower housing component 2781, a shelf 342
is provided having a pair of longitudinally spaced and slightly transversely
offset
upstanding pins 344 and 346 around which the actuator cord passes as shown in
Fig.
18. It has been found that by passing the actuator cord around the pins,
additional.
friction is established and improves the smoothness with which the tilting
mechanism
of the present invention operates. As will be appreciated, the rearmost pin
346 is
transversely aligned with the arcuate notch 300 previouslydescribed in the
large
cradle 296 so that as the actuator cord 140' extends laterally from the
upstanding
rearmost pin 348 to the bobbin 266 within the cradle, it remains substantially
perpendicular to the longitudinal axis of the bobbin whereby the actuator cord
can be
i5 desirably fed onto the bobbin to dependably follow the helical groove 236'
provided
in the tapered surface of the bobbin.
As will be appreciated, when the actuator cord 140' is being wrapped around
larger diameter portions of the bobbin, in order to feed the actuator cord
substantially
perpendicularly to the bobbin, it needs to be fed to the bobbin at a
relatively low
~ location but as the cord is fed to the bobbin towards the smaller diameter
portions, in
order to retain the perpendicular feeding, the cord must be fed'at a higher
location.
The arcuate edge 348 of the notch 300 in the cradle, which becomes an arcuate
slot 349 (Fig. 23) when the upper component of the housing 278 overlies the
lower
component, assures that the actuator cord is fed to the bobbin at a
substantially
perpendicular angle for most dependable operation of the tilt system.
The upper component 278u of the housing 278, while not being a precise
mirror itnage to the lower component 2781, has cooperating dividers and
cradles so as
to confine the aforenobed operative components of the tilt system for
dependable
operation. Of course, divider walls in the upper component overlie the bearing
seats
in the lower component and further the upper component is provided with a pair
of
apertures 350 for receiving the upper end of the upstanding pins 344 and 346
so that
the actuator cord 140' will retain its desired passage around the pins. While
not being
shown, complementary circular seats and holes are provided for receiving the
upper
16
CA 02467357 2004-05-17
ends of the pulleys 330 so they are confined between the upper and lower
components
of the housing and rotatably seated therein. Of course, screw-type fasteners
352
(Fig. 18) are provided for releasably securing the upper and lower components
together once the operative components have been positioned therein:
As mentioned previously, the mounting or support disc 274 is provided
beyond the outer end wall 314 of the lower housing compartment and rotates
with the
spur gear 272 to which it is operatively connected. As best sin in, Figs. 16-
18, the
mounting disc Has an arcuate slot 354 formed therein adjacent to its periphery
3~6 and
along the periphery of the disc; adjacent to the arcuate slot, a bead 358
projects
radially outwardly. .
The bracket 280 on which the headrail 105' is mounted has a pocket or seat
360 as best seen in Fig. 20 which releasably retains the disc 274 and the
pocket has an
arcuate surface 362 as seen in Figs. l6 and 17 having a, detent 364 therein
that
matingly and releasably receives the bead 358. It is important to note that
both the
bead and the detent themselves have arcuate surfaces.
In accordance with the operation of the blind assembly of this embodiri~ent,
when the bobbin 266 is rotated by the actuator cord 140' and resisted by the
constant
tension spring 269, the spur gear 272 is rotated by the gear assembly
240° which in
rum causes the mounting disc to rotate. 'Ihe mounting disc is releasably
connected to
the mounting bracket 280, however, aad as long as the bead 358 is seated in
the detest
364, the disc 274 and bracket remain: in a fixed relationship. Of course, the
bobbin is
trying to rotate the disc, but since the disc does not rotate relative to the
fixed bracket,
the headrail 105' is caused to rotate in reaction thereto thereby tilting the
headrail
between first and second closed positions wherein the transverse direction of
the
headrail is substantially vertical and parallel to the architectural opening
in which it is
mounted. Of course, the headrail can be stopped at any position between the
two
closed extremes and, for example, one position would7be a fully open position
wherein the headrail and consequently the supported slats in the covering are
horizontally disposed and perpendicular to the architectural opening.
Typically, the limits of pivotal movement of the headrail 105' can be
controlled by the amount of cord 140' wrapped on the bobbin 266 so that when
the
headrail reaches one of the extreme closed positions, rotation is stopped
b~ause the
actuator cord has been fully unwrapped from or wrapped onto the bobbin.
However,
17
CA 02467357 2004-05-17
should the system be improperly threaded such that an operator may continue to
pull
on the actuator cord and force continued pivotal movement of the headrail,
which is
inhibited by its abutment with an adjacent depending slat 130', damage to the
system
is avoided because the bead 358 on the mounting disc 274 will snap out of the
detent .
364 thereby allowing the mounting-disc and the bobbin 266 to continue
to,rotate, but
now, relative to the bracket. Of course, to reset the system, the bead is
simply
repositioned in the detent to releasably fix the disc relative to the bracket.
While the axis of the disc 274 remains fixed relative to the bracket 280, the
bead 358 is allowed to separate from the detent 364 as the arcuate slot 354.
formed in
the mounting disc permits a slight inward flex {Fig. 17) of the bead and thus
the body
of the disc. Conversely, when the bead is again aligned with the detent, a
resiliency
inherent in the mounting disc forces the bead hack into the detent. It will be
appreciated that the material from which the mounting disc is made needs to
have
some resiliency and many plastic materials are suitable. ',
Although the present invention has been described with a certain degree of
particularity, it is understood that the disclosure has been made by way of
example,
and changes in detail or structure may be made without departing from the
spirit of
the invention as dei~tned in the appended claims.
18
