Note: Descriptions are shown in the official language in which they were submitted.
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SELF-RAISING WINDOW COVERING
Field of Invention
The present invention relates to a window covering that may be
raised without the need to apply a force to either a control mechanism or the
window covering itself as the window covering is opened. In particular, the
present
invention relates to a window covering having a control mechanism configured
to
exert an upward force on the shade element and bottom rail that is of
sufficient
magnitude to raise the shade element and bottom rail without additional force
being
applied by the user during raising.
Background of the Invention
Window shades and coverings are found in many applications and
used to regulate the amount of light entering a room, and to provide aesthetic
appeal to a decor. Such window shades and coverings take many forms, including
roller shades, Roman shades, Venetian blinds, and cellular shades.
Conventional
cellular or pleated shades utilize cord locks or a transmission mechanism to
raise,
lower and position the window covering in a desired position. With window
coverings utilizing a cord lock, cords run up through the folded fabric,
across the
inside of a head rail and exit through a locking mechanism. Other cellular
shades
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include a transmission mechanism and a continuous loop cord that is pulled by
a
user to raise and lower the window shade. Roman shades and Venetian blinds
also
tend to include raising cords that are secured to a lower bar or bottom rail.
There are some disadvantages to these designs. Cords present the
potential hazard of a child getting caught in or strangled by the exposed
control
cord. Cords also tend to distract from the aesthetics of a window covering in
that
they extend along the face of the window covering and, when the window shade
is
opened, must either be wrapped on a hook or just left on the floor. With
window
coverings that utilize cord locks, the cords also experience substantial wear
due to
friction against surfaces as a result of raising and lowering of the window
covering.
Other window coverings include common roller shades, which
operate in the absence of a cord. These roller shades include a wound torsion-
spring retraction mechanism in combination with a clutch or locking mechanism
mounted with a roller onto which the shade is rolled and collected. In
operation, a
roller shade is pulled down by a user to a desired location, where it is
locked in
place by the clutch or locking mechanism. To unlock and release the shade so
that
it may be raised, the user typically pulls on a bottom rail of the shade,
extending the
shade sufficiently to disengage the internal clutch or locking mechanism
within.
When the clutch or locking mechanism is disengaged and the user releases the
shade, the shade is retracted using the torsion-spring driven retraction
mechanism.
Known roller shades, however, are only operable with flat shade material which
rolls up neatly into a confined location.
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The mechanism utilized in such roller shades is not compatible with
other window coverings, such as cellular shades, Venetian blinds, and Roman
shades. As roller shades are raised, the amount of shade being lifted
decreases such
that a constant force torsional spring member is capable of applying the
necessary
winding or upward force throughout the opening range. By contrast, a similar
lifting mechanism is typically unsuitable in cellular shades, Venetian blinds,
and
Roman shades. In these types of window coverings the material of the shade
element is typically gathered by raising a bottom member, such as a bottom
rail,
and increasing amounts of weight are gathered on the bottom member as the
window covering is raised. The reason for this is that the shade material or
shade
element increasingly stacks on the bottom rail as the bottom rail rises, which
increases the load on the lifting mechanism.
In order to address this increasing weight, very strong torsional
springs have been used to accommodate the maximum weight of the shade. One
drawback to this approach, however, is that the rate at which the window
covering
is retracted may be too fast and uncontrolled. One attempt to address this
problem
is found in U.S. Patent No. 6,666,252, issued to Welfonder. This patent
teaches the
use of a fluid brake to control the rate at which the raising cords are
retracted
throughout the raising process. Another approach that has been used is shown
in
U.S. Patent No. 6,056,036, issued to Todd, which employs a mechanical friction
member to continuously slow the rate of retraction. One problem with these
approaches has been that the spring utilized exerts a force that makes it
difficult for
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a user to overcome when attempting to lower the shade. Excessive pulling force
by
the user often results in damage to the window covering.
AIternatively, variable force springs have been used. Such variable
force springs are substantially more complicated in use and manufacture.
Therefore, there is a need for a window covering raising rnechanism
for window coverings such as Venetian blinds, cellular shades and Roman shades
that is self-raising and overcomes the foregoing problems.
Summary of the Invention
The present invention relates to a self-raising window covering and
a control mechanism for the window covering. In particular, the window
covering
is a self-raising window covering that includes a head rail, a shade element,
such as
a cellular panel, blind slats, or Roman shade material, a bottom rail, at
least one
raising cord operatively connected at a first end to the bottom rail, and a
control
mechanism. The head rail may define an elongated channel wherein the control
mechanism is disposed therein. In some embodiments, the control mechanism
includes a drive axle and a drive unit operatively connected with the drive
axle.
The drive unit, which may be a constant force spring, is adapted to provide a
substantially constant rotational force on the drive axle.
At least one cord winding assembly is also provided in co-axial
relation with the drive axle. Typically, the number of cord winding assemblies
will
be the same as the number of raising cords. However, in some instances, one
cord
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winding assembly may be adapted to operate with multiple cords. The cord
winding assembly includes at least one winding drum operatively connected to a
second end of the raising cord and having a tapered portion. The cord winding
assembly also includes a rotatable positioning member for moving the cord
winding assembly laterally along the drive axle upon rotation of the
positioning
member. In a preferred embodiment, the positioning member is a threaded
tubular
member connected to the winding drum. The cord winding assembly is adapted to
translate the rotational force on the drive axle to a raising force on the
raising cord,
wherein the raising force is greater than a total downward force exerted by
the
shade element and bottom rail throughout the range of opening and closing. In
a
preferred embodiment, the cord winding assembly is rotationally secured with
the
drive axle by a hub member adapted to engage the cord winding assembly and the
drive axle. The hub member may be in a sliding relationship with the tapered
portion of the cord winding assembly.
A clutch member or locking member is also operatively connected
with the axle and adapted to releasably lock the drive axle in a desired
position. In
a preferred embodiment, the clutch member comprises a reciprocator disposed
coaxially relative to the drive axle and movable between a released position
and a
locked position, and a spring member connected to the reciprocator and
operable to
either tighten or relax the hold of the reciprocator on the drive axle. The
reciprocator is configured to cause the spring member to tighten on the drive
axle
in the locked position for blocking a rotation of the drive axle against the
rotational
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force applied by the drive unit, and cause the spring member to relax the
drive axle
in the released position to permit a rotation of the drive axle under the
rotational
force applied by the drive unit
Brief Description of the Drawings
FIG. 1 is a perspective view, partly in cutaway, of a preferred
embodiment of a window covering according to the present invention;
FIG. 2 is an exploded perspective view of the single spring coil
drive unit of FIG. 1;
FIG. 3 is a side elevational cross section view of the single spring
coil drive unit of FIG. 1;
FIG. 4 is a side elevational cross section view of an alternative
single spring coil drive unit;
FIG. 5 is a side elevational cross section view of a double spring
drive unit;
FIG. 6 is a side elevational cross section view of an alternative
double spring drive unit;
FIG. 7 is an exploded perspective view of the cord winding
assembly shown in FIG. 1;
FIG. 8A is a front elevational view of the window covering of FIG.
1 in a closed position and with the head rail in cross section;
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FIG. 8B is a front elevational view of the window covering of FIG.
1 in a partially open position and with the head rail in cross section;
FIG. 9A is a perspective view of a preferred clutch member when
the window covering is in a fully raised position;
FIG. 9B is a cross sectional view of the clutch member of FIG. 9A;
FIG. 10A is a perspective view of the clutch member of FIG. 9A as
the user pulls down on the window covering;
FIG. lOB is a cross sectional view of the clutch member of FIG.
10A;
FIG. 1 lA is a perspective view of the clutch member of FIG. 9A as
the user releases the window covering;
FIG. 11B is a cross sectional view of the clutch member of FIG.
11A;
FIG. 12A is a perspective view of the clutch member of FIG. 9A as
the user pulls down on the window covering to release the clutch member;
FIG. 12B is a cross sectional view of the clutch member of FIG.
12A;
FIG. 13A is a perspective view of the clutch member of FIG. 9A as
the window covering self-raises;
FIG. 13B is a cross sectional view of the clutch member of FIG.
13A;
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FIG. 14 is a perspective view of an alterative embodiment of a
window covering according to the present invention with a deceleration member;
FIG. 15A is a side elevational cross section view of the deceleration
member of FIG. 14 disengaged from one cord winding assembly;
FIG. 15B is a side elevational cross section view of the deceleration
member of FIG. 14 engaging one cord winding assembly; and
FIG. 15C is a side elevational cross section view of the deceleration
member of FIG. 14 when the window covering is fully raised.
Detailed Description of Preferred Embodiments
The invention disclosed herein is susceptible to embodiment in
many different forms. Shown in the drawings and described in detail
hereinbelow
are preferred embodiments of the present invention. The present disclosure,
however, is only an exemplification of the principles and features of the
invention,
and does not limit the invention to the illustrated embodiments.
Referring to FIGURE 1, an embodiment of a self-raising window
covering 10 according to the present invention is shown. A head rail 12
defining a
channel is provided. A pair of drive units, such as spring units 14 and 16 are
coaxially mounted about a drive axle 18. Also mounted on drive axle 18 are
cord
winding assemblies 20 and 22. Each of cord winding assemblies 20 and 22
includes a frustoconical winding drum 24 and 26, and a threaded tubular member
32 and 34, respectively. Raising cords 28 and 30, which are shown as wound on
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winding drums 24 and 26, are secured at an end to the winding drums 24 and 26.
In this embodiment, a clutch 36 is also provided and co-axially mounted on the
drive axle 18. Each of these components is discussed in greater detail below.
Window covering 10 further includes a shade element, such as cellular shade
material 38 and a bottom member, such as bottom rail 40. The term "cord" as
used
may encompass a cord, strip, ribbon, string or any similar flexible elongated
elements that are suitable for supporting the suspended shade element, and can
be
wound or unwound to deploy or retract the shade element. A relatively short
length
of cord 42 can also be provided so that the user can pull down the window
covering
and, as will be discussed in further detail, release the clutch so that the
window
covering will retract itself.
Referring to FIG. 2, a preferred embodiment of the spring unit 14 is
shown. The spring unit 14 comprises a spring casing 42, a spring axle 44, a
constant force coil spring 46 and a cover 48. The coil spring 46 and the
spring axle
44 are secured within the casing 42, which is closed by cover 48. A first end
50 of
the coil spring 46 is secured to the spring axle 44, which is coaxially
connected to
the drive axle 18 (FIG. 1). In this preferred embodiment, the coil spring is
configured to provide sufficient rotational force to the drive axle 18 and
winding
drums 24 and 26 to raise the shade element and bottom rail. Other alternative
embodiments of spring units are also possible, such as shown in FIGS. 3-6.
For example, a suitable spring unit 114 shown in FIG. 3 may include
a coiled spring member 146 having a first end secured with a first spring axle
142
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that connects to the drive axle 18 shown in FIG. 1, and a second end secured
with a
second spring axle 144 that is offset from the first spring axle 142. The
coiled
spring 146 in a relaxed position may be initially wound around the second
spring
axle 144. As the shade element is pulled downward, the coiled spring 146 may
stretch out from the second spring axle 144 and progressively wind around the
first
spring axle 142. This configuration of the spring unit 114 may be suitable
when
the used coiled spring 146 has a greater length to allow a longer deployment
range
of the shade element.
FIG. 4 illustrates another suitable spring unit 214, which is similar to
the embodiment shown in FIG. 3 except that the second end of the coiled spring
does not connect to any second spring axle. Instead, the coiled spring 246
winds on
itself at its second end, while the first end 252 of the coiled spring 246
connects to
a single spring axle 218 connected to the drive axle 18 shown in FIG. 1.
Still other suitable embodiments of spring units are shown in FIGS.
5 and 6. In FIG. 5, spring unit 314 includes an assembly of two coiled springs
346
and 348 that may be used to provide a greater raising force for the shade
element.
The first coiled spring 346 has its first end connected to a first spring axle
344, and
the second coiled spring 348 has its first end connected to a second spring
axle 345.
The second end of the first coiled spring 346 and the second end of the second
coiled spring 348 respectively connect to a third spring axle 318 located
between
the first and second spring axles 344 and 345 and connected to the drive axle
18.
As the shade element is pulled downward, the coiled springs 346 and 348 may
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respectively stretch out from the first and second spring axle 344 and 345 to
progressively wind around the third spring axle 318 to apply an increased
raising
force on the drive axle 18. In FIG. 6, the shown embodiment is very similar to
that
shown in FIG. 5 except that the two coiled springs 446 and 448 that wind on
the
axle 418 connected to the drive axle do not connect with second spring axles.
Although each of the embodiments shown utilizes a spring as the driving
mechanism for the drive unit, it should be understood that any suitable
mechanism
for imparting a rotational force on the drive axle may be utilized.
Referring again to FIG. 1, the rotational force exerted upon a drive
axle 18 causes the cord winding assemblies 20 and 22 to rotate and translate
for
winding the cords 28 and 30, which thereby raises the shade eIement 38
vertically
toward the head rail 12. Further details on a preferred embodiment of a cord
winding assembly are provided with reference to FIG. 7.
Cord winding assembly 20 is mounted co-axially with the drive axle
18 that passes through a fixed housing comprised of a frame 64 and upper cover
65.
The cord winding assembly 20 includes a winding drum 24 and a rotational
positioning member, such as threaded tubular member 32, fixedly connected at
an
end of the winding drum 24. The cord winding assembly 20 is preferably mounted
on the drive axle 18 via a hub member, such as adapter 60 that is configured
to
, transmit rotational movement between the drive axle 18 and the cord winding
assembly 20 while allowing a relative translation movement therebetween. In
some embodiments, the adapter 60 may be coaxially mounted inside a central
hole
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of the winding drum 24, and include a through hole for mounting the drive axle
18.
To transfer rotational movement while perrnitting smooth relative translation
between the winding drum 24 and the adapter 60, a peripheral surface of the
adapter 60 may be provided with radial portions that contact with ribs
protruding
radially inward from the surface of the central hole of the winding drum 24.
Further, the threaded tubular member 32 engages with toothed rollers 66, which
are
rotatably mounted to frame 64 and bracket 68 fixedly secured in head rail 12.
Rotational movements thereby can be transferred between the drive axle 18 and
the
cord winding assembly 20, while smooth relative translations with reduced
frictions
are permitted therebetween. In addition, the engagement via the adapter 60 and
the
threaded tubular member 32 allows an improved support of the load of the
suspended components, e.g. shade element 38 and bottom rai140.
The winding drum 24 is tapered and is preferably frustoconical in
shape, and may include striations or grooves to improve gripping of the cord
28
wound on the surface of the winding drum 24. An end of the raising cord (not
shown) is secured towards the larger diameter end 62 of the winding drum 24.
As
the cord winding assembly 20 rotates and translates in a direction to wind the
raising cord 28, the raising cord is wrapped around increasingly narrower
portions
of the winding drum 24.
Refemng to FIGS. 8A and 8B, the raising operation of the window
covering is shown. When the shade element 38 is fully deployed, as shown in
FIG.
8A, the raising cord 28 is fully extended from a wider portion of the winding
drum
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24. As the bottom rail 40 rises under the resilient force of the spring units
14 and
16, as shown in FIG. 8b, the threaded engagement between the threaded tubular
member 32 and rollers 66 causes the rotating cord winding assembly 20 to move
laterally within the head rail 12, such that the raising cord winds along the
winding
drum 24 towards its narrower end.
Because the rising bottom rai140 causes the shade element 38 to
collapse and stack up thereon, the total weight being raised by the resilient
force
applied by spring units 14 and 16 thus increases. The load on the spring units
is
now described with reference to one of the spring units. The load on one
spring
unit 14 is derived with an adequate scale factor from a momentum M on the
drive
axle 18 that can be approximated by the product between the suspended weight
W,
including the weight of the bottom rail plus the amount of shade element 38
stacked thereon, and a winding radius R of the winding drum 24. As the bottom
rai140 rises, W will increase, and R will decrease because the raising cord 28
winds
on increasingly narrower portions of the tapered winding drum 24 that slide
with
reduced frictions owing to the adapter 60 and threaded tubular member 32 and
adapter 60. Accordingly, even though the suspended weight W increases, the
load
M on one spring unit 14 can be kept at a level that varies slightly and can be
overcome by the constant force spring 46 (FTG. 2) to fully raise the bottom
rail 40
and shade element 38. In order to lower the window covering, a user exerts an
approximately. constant pulling force regardless of the position in height of
the
window covering. With the cord winding assemblies 20 and 22, spring units 14
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and 16 of constant force thus can be suitably used to raise a suspended weight
charge W that increases as it rises.
In some embodiments, such as the one depicted, the shade element
itself may have an effect on the total downward force or suspended weight. For
example, where the shade element is a cellular window covering, an inherent
upward spring bias to the material may serve to decrease the total downward
force.
The total contribution of this spring bias varies depending on the degree to
which
the cellular window covering is extended.
As explained, as the window covering opens, the total weight
suspended increases and the total raising force decreases. As such, the rate
at
which the window cover raises decreases as it nears a fully opened condition.
Therefore, the shortcoming typically found in roller shade where the shade is
retracted to quickly and violently avoided.
Referring again to FIG. 6, the clutch member 36 is provided in order
to lock the shade element 38 and bottom rail 40 in a desired position. Clutch
member 36 is mounted coaxially with the drive axle 18 and is configured to
unlock
the drive axle 18 as the user pulls down the bottom rai140 to stretch the
shade
element 38, and to lock the drive axle 18 when the user releases the bottom
rai140
at the desired height. When the user pulls down slightly on the bottom rail
again,
. the clutch disengages and allows the bottom rai140 to be raised by the
spring units
14 and 16. Referring to FIG. 9A and 9B, the clutch member 36 includes a casing
70 that has fixed protrusions 72 and 74. A collar 76 rotating with the drive
axle 18
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is provided, which reciprocates axially along the drive axle 18. A
reciprocator 78
is co-axially mounted over collar 76 and is movable both rotatably and axially
therewith. A spring 80 having a first end 82 and a second end 84 is provided
between collar 76 and reciprocator 78.
FIGS. 9A and 9B show the clutch when the window covering 10 is
in a fully raised position. Spring 80 is in a relaxed condition with second
end 84 in
an abutting relationship with protrusion 74. As shown in FIGS. 10A and IOB,
when the user pulls on the bottom rail (not shown), a clockwise rotation (as
shown)
of the axle 18 and the collar 76 occurs and causes the second end 84 of the
spring
80 to disengage from protrusion 74. Spring 80 tightens on collar 76 such that
rotation of the collar 76 is transmitted to reciprocator 78 via the contact
between
first end 82 of the spring 80 and reciprocator 78, which brings reciprocator
78 into
abutment with protrusion 72. As the reciprocator 78 abuts against protrusion
72,
the spring 80 relaxes again and the drive axle 18 may continue to rotate as
the user
further pulls on the bottom rail. Referring to FIG. 1 1A and 11B, as the user
releases the bottom rail at a desired height, spring 80 tightens on collar 76
and the
drive axle 18, urged by the spring units 14 and 16 (FIG. 1), rotates
reciprocator 78
in a counterclockwise direction until it reaches a locking position where
protrusion
72 abuts against a stop 79 on'the reciprocator 78. In this locking position,
the
spring 80 tightens to stop rotation of the drive axle 18 against the raising
force
exerted by spring units 14 and 16. Referring to FIGS. 12A and 12B, as the user
pulls down slightly on the bottom rail, the spring 80 tightens and a resulting
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clockwise rotation of the drive axle 18 and collar 76 causes the reciprocator
78 to
disengage from the locking position to a release position. When the user
releases
the bottom rail as shown in FIGS 13A and 13B, the spring units 14 and 16 cause
the drive axle 18 to rotate in a counterclockwise direction to bring second
end 84 of
the spring 80 into engagement with protrusion 74, and thereby loosening spring
80,
which permits drive axle 18 to continue rotating and fully opening the window
covering.
An alternative embodiment of the window covering according to the
present invention is shown in FIG. 14. In most aspects, this embodiment is the
same as the ones previously discussed. Window covering 510 includes a head
rail
512 having a pair of spring units 514 and 516 mounted with a drive axle 518.
Cord
winding assemblies 520 and 522 are also provided. Raising cords 528 and 530
pass
through shade element 538 and are connected with bottom rai1540. In addition,
at
least one deceleration member 550 is provided. Deceleration member 550 is
engageable with one cord winding assembly 522 to slow down the rise of the
bottom rai1540 as it approaches the head rail.
The preferred embodiment of the deceleration member 520 is shown
in FIGS_ 15A - 15C. In the position of FIG. 15A, the cord winding assembly 522
is
disengaged from the deceleration member 550. As the cord winding assembly 522
winds the cord 526, the cord winding assembly 522 also moves towards the
deceleration member 550. As the cord winding assembly 522 engages with a plate
552 of the deceleration member 550 as shown in FIG 15B, the rotation of the
cord
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winding assembly 522 causes the plate 552 to rotate. The plate 552 is
connected to
an axle sleeve 554, which is in contact with a decelerating member, such as
viscous
oil liquid, contained inside a housing 556. The sleeve 554 is configured to
achieve
a resistant contact with the decelerating member to decelerate the rotation of
the
cord winding assembly. For example, protrusions or fins may be provided on the
axle sleeve 554. The rate at which the bottom rail is raised by the spring
units 514
and 516 is slowed as the bottom rail reaches the head rail so that the bottom
rail
more smoothly stops at a fully opened position.
The foregoing descriptions are to be taken as illustrative, but not
limiting. Still other variants within the spirit and scope of the present
invention
will readily present themselves to those skilled in the art.
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