U.S. patent application number 13/402454 was filed with the patent office on 2013-02-07 for window shade having a resistance balancing mechanism.
This patent application is currently assigned to TEH YOR CO, LTD.. The applicant listed for this patent is Chin-Tien HUANG, Fu-Lai YU. Invention is credited to Chin-Tien HUANG, Fu-Lai YU.
Application Number | 20130032300 13/402454 |
Document ID | / |
Family ID | 47626193 |
Filed Date | 2013-02-07 |
United States Patent
Application |
20130032300 |
Kind Code |
A1 |
YU; Fu-Lai ; et al. |
February 7, 2013 |
Window Shade Having a Resistance Balancing Mechanism
Abstract
A window shade comprises first and second rails, and a shading
structure and a suspension cord connected between the first and
second rails. The second rail includes a resistance balancing unit
and a cord winding unit to which the suspension cord respectively
connects. The resistance balancing unit comprises a housing having
an abuttal surface, a pulley pivotally connected with the housing,
and a torsion spring. The pulley has a winding portion around which
the suspension cord is wrapped, and a shaft portion extending
coaxial to the winding portion from a side thereof. The torsion
spring is tightly mounted around the shaft portion and has at least
one end. The pulley when rotating in one direction drives the end
of the torsion spring to push against the abuttal surface of the
housing, whereby the torsion spring loosens to allow rotation of
the pulley relative to the torsion spring.
Inventors: |
YU; Fu-Lai; (New Taipei
City, TW) ; HUANG; Chin-Tien; (New Taipei City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
YU; Fu-Lai
HUANG; Chin-Tien |
New Taipei City
New Taipei City |
|
TW
TW |
|
|
Assignee: |
TEH YOR CO, LTD.
Taipei
TW
|
Family ID: |
47626193 |
Appl. No.: |
13/402454 |
Filed: |
February 22, 2012 |
Current U.S.
Class: |
160/84.02 ;
242/371 |
Current CPC
Class: |
E06B 2009/2627 20130101;
E06B 2009/3222 20130101; E06B 9/322 20130101 |
Class at
Publication: |
160/84.02 ;
242/371 |
International
Class: |
A47H 5/032 20060101
A47H005/032 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 2011 |
TW |
100127779 |
Claims
1. A resistance balancing unit suitable for use with a window
shade, comprising: a housing having an abuttal surface; a pulley
pivotally assembled with the housing, the pulley having a winding
portion around which a suspension cord is wrapped, and a shaft
portion extending coaxial from a side of the winding portion; and a
torsion spring tightly mounted around the shaft portion and having
at least one end, wherein the pulley when rotating in one direction
drives the end of the torsion spring to push against the abuttal
surface of the housing, whereby the torsion spring loosens to allow
the pulley to rotate relative to the torsion spring.
2. The resistance balancing unit according to claim 1, wherein the
housing has a first face and a second face, the suspension cord
entering the housing from the first face, wrapping around the
winding portion, and extending outside the housing from the second
face.
3. The resistance balancing unit according to claim 2, wherein the
first face and the second face are substantially perpendicular to
each other.
4. The resistance balancing unit according to claim 2, wherein the
first face and the second face are substantially parallel to each
other.
5. The resistance balancing unit according to claim 2, wherein the
housing includes a blade assembled at the second face, the blade
and an edge of the housing defining a slit for passage of the
suspension cord.
6. The resistance balancing unit according to claim 5, wherein the
blade is movably assembled with the housing, and is operable to
press against the suspension cord.
7. The resistance balancing unit according to claim 1, wherein the
suspension cord wraps around the pulley about one or more turn.
8. A window shade comprising: a first rail; a second rail; a
shading structure disposed between the first rail and the second
rail; and at least a suspension cord connected between the first
and second rails; wherein the second rail includes a resistance
balancing unit and a cord winding unit, the suspension cord
respectively connecting with the resistance balancing unit and the
cord winding unit, the resistance balancing unit comprising: a
housing having an abuttal surface; a pulley pivotally connected
with the housing, the pulley having a winding portion around which
a suspension cord is wrapped, and a shaft portion extending coaxial
from a side of the winding portion; and a torsion spring tightly
mounted around the shaft portion and having at least one end,
wherein the pulley when rotating in one direction drives the end of
the torsion spring to push against the abuttal surface of the
housing, whereby the torsion spring loosens to allow the pulley to
rotate relative to the torsion spring.
9. The window shade according to claim 8, wherein the housing has a
first face and a second face, the suspension cord enters the
housing from the first face, wraps around the winding portion, and
extends outside the housing via the second face.
10. The window shade according to claim 9, wherein the first face
and the second face are substantially perpendicular to each
other.
11. The window shade according to claim 9, wherein the first face
and the second face are substantially parallel to each other.
12. The window shade according to claim 9, wherein the housing
includes a blade assembled at the second face, the blade and an
edge of the housing defining a slit for passage of the suspension
cord.
13. The window shade according to claim 12, wherein the blade is
movably assembled with the housing, and is operable to press
against the suspension cord.
14. The window shade according to claim 8, wherein the suspension
cord wraps around the pulley about one or more turn.
15. The window shade according to claim 8, wherein an adjustment
that increases a distance between the first and second rails causes
the suspension cord to unwind from the cord winding unit and drives
the pulley in rotation, which results in the end of the torsion
spring to push against the abuttal surface, whereby the torsion
spring is loosened and the pulley is allowed to rotate relative to
the torsion spring.
16. The window shade according to claim 8, wherein an adjustment
that reduces a distance between the first and second rails causes
the suspension cord between the first and second rails to become
loose, which results in the cord winding unit to wind the
suspension cord under a spring force.
17. The window shade according to claim 8, wherein the torsion
spring recovers a tightened state on the pulley to stop the pulley
when the first and second rails are stationary.
18. The window shade according to claim 8, wherein the resistance
balancing unit is spaced apart from the cord winding unit.
19. The window shade according to claim 8, wherein the cord winding
unit includes a casing, a winding drum, a coiled spring connected
with the winding drum, and a guide roller movable along a shaft
portion, the guide roller sliding along the shaft portion to
facilitate uniform winding of the suspension cord on the winding
drum during an adjustment that reduces a distance between the first
and second rails.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims priority to Taiwan Patent
Application No. 100127779 filed on Aug. 4, 2011.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to window shades.
[0004] 2. Description of the Related Art
[0005] Many types of window shades are currently available on the
market, such as Venetian blinds, roller shades and honeycomb
shades. The shade when lowered can cover the area of the window
frame, which can reduce the amount of light entering the room
through the window and provided increased privacy. A typical window
shade can include a top rail, a bottom rail, a shading panel and a
drive mechanism. The bottom rail is usually connected with a lower
end of the shading panel, whereas the drive mechanism is assembled
in the top rail. The drive mechanism can include a winding drum,
and an operating cord extending outside the top rail. A user can
actuate the operating cord to drive rotation of the winding drum,
which can raise or lower the shading panel.
[0006] While the use of the operating cord may be convenient for an
adult, there is the risk that children strangle on the operating
cords.
[0007] Therefore, there is a need for a window shade that is
convenient to operate, safer in use and address at least the
foregoing issues.
SUMMARY
[0008] The present application describes a window shade having a
resistance balancing unit that can be adjusted by raising or
lowering an elongated rail.
[0009] In one embodiment, the resistance balancing unit comprises a
housing having an abuttal surface, a pulley pivotally assembled
with the housing, and a torsion spring. The pulley has a winding
portion around which a suspension cord is wrapped, and a shaft
portion extending coaxial from a side of the winding portion. The
torsion spring is tightly mounted around the shaft portion and has
at least one end, wherein the pulley when rotating in one direction
drives the end of the torsion spring to push against the abuttal
surface of the housing, whereby the torsion spring loosens to allow
the pulley to rotate relative to the torsion spring.
[0010] In another embodiment, a window shade is described. The
window shade comprises a first rail, a second rail, a shading
structure disposed between the first rail and the second rail, and
at least a suspension cord connected between the first and second
rails. The second rail includes a resistance balancing unit and a
cord winding unit, the suspension cord respectively connecting with
the resistance balancing unit and the cord winding unit. The
resistance balancing unit comprises a housing having an abuttal
surface, a pulley pivotally connected with the housing, and a
torsion spring. The pulley has a winding portion around which a
suspension cord is wrapped, and a shaft portion extending coaxial
from a side of the winding portion. The torsion spring is tightly
mounted around the shaft portion and has at least one end, wherein
the pulley when rotating in one direction drives the end of the
torsion spring to push against the abuttal surface of the housing,
whereby the torsion spring loosens to allow the pulley to rotate
relative to the torsion spring.
[0011] At least one advantage of the window shades described herein
is the ability to conveniently adjust the shade by raising and
lowering the lower rail. Moreover, the assembly of the resistance
balancing unit in the window shade can allow to accurately hold the
shading structure at any height.
[0012] The foregoing is a summary and shall not be construed to
limit the scope of the claims. The operations and structures
disclosed herein may be implemented in a number of ways, and such
changes and modifications may be made without departing from this
invention and its broader aspects. Other aspects, inventive
features, and advantages of the invention, as defined solely by the
claims, are described in the non-limiting detailed description set
forth below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic view illustrating an embodiment of a
window shade in a downwardly deployed stage;
[0014] FIG. 2 is a schematic view illustrating the window shade in
an upwardly retracting stage;
[0015] FIG. 3 is a perspective view of a resistance balancing unit
assembled in the window shade shown in FIG. 1;
[0016] FIG. 4 is a cross-sectional view taken along section C1
shown in FIG. 3;
[0017] FIG. 5 is a cross-sectional view taken along section C2
shown in FIG. 3;
[0018] FIG. 6 is a bottom view of the resistance balancing
unit;
[0019] FIG. 7 is a front view illustrating a cord winding unit
assembled in the window shade shown in FIG. 1;
[0020] FIG. 8 is a top view of the cord winding unit shown in FIG.
7;
[0021] FIG. 9 is a partial cross-sectional view of the cord winding
unit;
[0022] FIG. 10 is a perspective view of the resistance balancing
unit as the second rail is adjusted toward the first rail;
[0023] FIG. 11 is a cross-sectional view taken along section C1
shown in FIG. 10;
[0024] FIG. 12 is a cross-sectional view taken along section C2
shown in FIG. 10;
[0025] FIG. 13 is a schematic view illustrating another embodiment
of a control module associating a resistance balancing unit with a
cord winding unit;
[0026] FIG. 14 is a schematic view detailing the construction of
the cord winding unit shown in FIG. 13;
[0027] FIG. 15 is a schematic view illustrating a window shade
provided with the resistance balancing unit and the cord winding
unit shown in FIG. 13;
[0028] FIG. 16 is a schematic view illustrating the window shade
shown in FIG. 15 adjusted upward;
[0029] FIG. 17 is a cross-sectional view illustrating another
embodiment of a resistance balancing unit;
[0030] FIG. 18 is a bottom view of the resistance balancing unit
shown in FIG. 17; and
[0031] FIG. 19 is a schematic view illustrating another variant
embodiment of a resistance balancing unit.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0032] FIGS. 1 and 2 are schematic views illustrating one
embodiment of a hand-pull type window shade 100. More particularly,
FIG. 1 shows the window shade 100 in a downwardly deployed state,
and FIG. 2 shows the window shade 100 in an upwardly retracting
state. The window shade 100 can include a first rail 102, a second
rail 104, a shading structure 106, suspension cords 108, resistance
balancing units 110 and a cord winding unit 112. The shading
structure 106 can have upper and lower ends respectively affixed
with the first rail 102 and the second rail 104. The resistance
balancing units 110 and the cord winding unit 112 can be
respectively installed in the second rail 104. In one embodiment,
two resistance balancing units 110 and one cord winding unit 112
can be provided to form a control module of the window shade 100,
the cord winding unit 112 being installed between and spaced apart
from the two resistance balancing units 110. Each of the suspension
cords 108 can have a first end fixedly attached with the first rail
102, and an opposite second portion respectively passing through
the resistance balancing units 110 and connected with the cord
winding unit 112. The cord winding unit 112 can have a
spring-driven mechanism that can be operable to wind the suspension
cords 108 when the second rail 104 rises. Once the second rail 104
reaches and is released at a desired height, all of the applied
forces including the spring force from the cord winding unit 112,
the weights of the shading structure 106 and the second rail 104,
and internal friction forces (including the resistive force
generated by the resistance balancing unit 110), can be balanced to
create an equilibrium condition. As a result, the second rail 104
can be held stationary at the desired height.
[0033] In one embodiment, the first rail 102 can be affixed with a
top portion of a window opening frame, and the second rail 104
provided with the resistance balancing units 110 and the cord
winding unit 112 can be suspended vertically from the first rail
102. In alternate embodiments, the positions of the first and
second rails can also be interchanged: the second rail 104 provided
with the resistance balancing units 110 and the cord winding unit
112 can be affixed with a top portion of a window opening frame,
whereas the first rail 102 can be suspended vertically from the
second rail 104.
[0034] Referring again to FIGS. 1 and 2, the shading structure 106
can be made of a fabric material, e.g., honeycomb structure formed
from a fabric material. In alternate embodiments, the shading
structure 106 can also have other types of constructions, e.g.,
slats, shading rows, etc.
[0035] FIG. 3 is a perspective view of the resistance balancing
unit 110, FIG. 4 is a cross-sectional view taken along section C1
shown in FIG. 3, FIG. 5 is a cross-sectional view taken along
section C2 shown in FIG. 3, and FIG. 6 is a bottom view of the
resistance balancing unit 110. As shown in FIGS. 3-6, the
resistance balancing unit 110 can include a housing 114, a pulley
116, a torsion spring 118 and a movable blade 120. The housing 114
can have a generally rectangular shape, including a first face 114A
and a second face 114B. In the illustrated embodiment, the first
face 114A and the second face 114B can be exemplary perpendicular
to each other. The first face 114A can have a hole 122. The second
face 114B can be formed with a slotted window 124 where the blade
120 is movably assembled, and a slit 126 can be defined between the
blade 120 and a side edge 124A of the window 124 for passage of the
suspension cord 108.
[0036] Moreover, an interior of the housing 114 can define a first
receiving space 128A and a second receiving space 128B that are at
least partially separated from each other by a sidewall 130. The
first receiving space 128A can respectively communicate with the
hole 122 and the slit 126.
[0037] The pulley 116 can include a winding portion 116A and a
shaft extension 116B. The shaft extension 116B can project from a
side of the winding portion 116A along a same axis of rotation. In
one embodiment, the winding portion 116A and the shaft extension
116B can be formed integrally with the pulley 116. When the pulley
116 is pivotally assembled with the housing 114, the winding
portion 116A can be placed in the first receiving space 128A, and
the shaft extension 116B can pass through an opening of the
sidewall 130 and be disposed in the second receiving space 128B.
Accordingly, when the pulley 116 rotates relative to the housing
114, the winding portion 116A and the shaft extension 116B can
rotate in unison about a same axis.
[0038] The torsion spring 118 can be tightly mounted on an outer
peripheral surface of the shaft extension 116B. In one embodiment,
the torsion spring 118 can be exemplary a bidirectional torsion
spring. Two protruding ends 118A and 118B of the torsion spring 118
can be respectively disposed adjacent to two abuttal surfaces 132
of the housing 114 adjacent to the second receiving space 128B.
[0039] The suspension cord 108 can travel into the first receiving
space 128A through the hole 122 of the first face 114A, wrap about
one and half turn around the winding portion 116A, and extend
outside the housing 114 via the slit 126 on the second face 114B.
Accordingly, a first portion 108A of the suspension cord 108
outwardly adjacent to the first face 114A can be substantially
perpendicular to a second portion 108B of the suspension cord 108
outwardly adjacent to the second face 114B. Moreover, owing to the
pressure applied by the blade 120, the second portion 108B of the
suspension cord 108 passing through the slit 126 can be kept in
contact with the blade 120 and the side edge 124A of the window
124. It is worth noting that because the suspension cord 108 can be
wrapped several turns around the pulley 116 (in particular at least
one or more turn), the contact area between the suspension cord 108
and the pulley 116 can be increased, which can create suitable
frictional resistance to balance other forces exerted on the second
rail 104. As a result, the second rail 104 can be kept stationary
at any height in a stable manner.
[0040] FIGS. 7 and 8 are respectively front and top views
illustrating the cord winding unit 112, and FIG. 9 is a partial
cross-sectional view of the cord winding unit 112. The cord winding
unit 112 can include a casing 140, two winding drums 142, two coil
springs 143 and two guide rollers 144. Two opposite sides of the
casing 140 can respectively include openings 146 and 148 for the
passage of the two suspension cords 108. The two guide rollers 144
can be movably assembled with two shaft portions 145 adjacent to
the openings 146 and 148, respectively. Accordingly, each guide
roller 144 can slide along the associated shaft portion 145.
[0041] Each of the winding drums 142 can be pivotally connected
with the casing 140. An upper end of each winding drum 142 can be
affixed with a gear 150. The pivot axes of the winding drums 142
can be parallel to the shaft portions 145, and substantially
perpendicular to the pivot axis of the pulley 116. Moreover, the
casing 140 can also be pivotally connected with a pivot shaft 152
disposed between the two winding drums 142. The pivot shaft 152 can
be substantially parallel to the pivot axes of the winding drums
142, and can have an upper end affixed with a transmission gear
154. The transmission gear 154 can be respectively engaged with the
gears 150 of the winding drums 142, whereby the winding drums 142
can rotate in unison to concurrently wind or unwind the suspension
cords 108.
[0042] Pressing arms 156 can be respectively mounted adjacent to
the winding drums 142, and can act to ensure that the suspension
cords 108 are wound tightly around the winding drums 142. Each of
the pressing arms 156 can have a first end pivotally connected with
the casing 140, and a second end that presses the corresponding
suspension cord 108 against the surface of the winding drum 142. As
each suspension cord 108 progressively winds around the associated
winding drum 142, the pressing arm 156 can pivotally displace for
adjustment.
[0043] As shown in FIG. 9, the coiled springs 143 can be
respectively assembled in the winding drums 142. Each of the coiled
springs 143 can have a first end anchored with the casing 140, and
a second end connected with the associated winding drum 142. The
coiled springs 143 can respectively bias the winding drums 142 to
rotate in directions for winding the suspension cords 108.
[0044] When the cord winding unit 112 is assembled, the two
suspension cords 108 can respectively travel into the casing 140
via the openings 146 and 148, wrap around the two guide rollers
144, and then connect and wind on the two winding drums 142. Biased
by the coiled springs 143, the winding drums 142 can rotate to wind
the suspension cords 108. While the winding drums 142 are winding
the suspension cords 108, the guide rollers 144 can respectively
slide along the shaft portions 145 so that the suspension cords 108
can be respectively wound in turns uniformly distributed on the
surfaces of the winding drums 142.
[0045] Exemplary operation of the window shade 100 is described
hereafter with reference to FIGS. 1-11. First referring to FIGS. 1
and 3-9, the second rail 104 can be pulled downward in a direction
F1 (i.e., in a direction that increases the distance between the
first rail 102 and the second rail 104), which causes each
suspension cord 108 to unwind from the associated winding drum 142
and drives the winding drum 142 in rotation. As it unwinds from the
winding drum 142, the suspension cord 108 can drive the pulley 116
to rotate in a direction (e.g., in the anticlockwise direction
shown in FIG. 5) to push the end 118A of the torsion spring 118
against the abuttal surface 132. As a result, the torsion spring
118 initially in a tightened state can loosen to permit rotation of
the pulley 116 relative to the torsion spring 118. Accordingly, the
length of the suspension cords 108 between the first and second
rails 102 and 104 can progressively increase.
[0046] When the user stops pulling the second rail 104 downward
(i.e., the first and second rails 102 and 104 are stationary), each
torsion spring 118 can recover a tightened state on the associated
pulley 116. As a result, the pulleys 116 no longer rotate, and a
frictional resistance can be created owing to the wrapping of the
suspension cords 108 around the pulleys 116. Accordingly, the
spring forces exerted by the coiled springs 143 on the winding
drums 142 can counterbalance the weight applied on the second rail
104, the resistance generated by the resistance balancing units
110, and other internal frictional forces to stop the winding drums
142. Owing to the balance of all the forces applied thereon, the
second rail 104 can be kept stationary at the desired position in a
stable manner.
[0047] As shown in FIG. 2, when the second rail 104 is moved upward
in a direction F2 (i.e., in the direction that reduces the distance
between the first and second rails 102 and 104), the portions of
the suspension cords 108 between the first and second rails 102 and
104 can become loose (i.e., forming a slack). As a result, the
winding drums 142 of the cord winding unit 112 can reversely rotate
to wind the suspension cords 108.
[0048] In conjunction with FIG. 2, FIGS. 10-12 are schematic views
illustrating intermediary stages of the resistance balancing unit
110 during an upward displacement of the second rail 104. More
particularly, FIG. 10 is a perspective view of the resistance
balancing unit 110, FIG. 11 is a cross-sectional view taken along
section C1 shown in FIG. 10, and FIG. 12 is a cross-sectional view
taken along section C2 shown in FIG. 10. As the winding drum 142 is
winding the suspension cord 108, the pressure from the blade 120
can keep the portion of the suspension cord 108 that is located
between the resistance balancing unit 110 and the cord winding unit
112 in a tensioned state. Accordingly, the suspension cord 108 can
smoothly slip around the pulley 116, and be wound around the
winding drum 142 without being interlaced. The length of the
suspension cords 108 between the first and second rails 102 and 104
thus can progressively shorten.
[0049] When the user stops moving the second rail 104 upward, each
torsion spring 118 can recover a tightened state on the associated
pulley 116. As a result, each of the pulleys 116 is stopped, and a
frictional resistance is created owing to an increased contact area
between the suspension cord 108 and the pulley 116. Accordingly,
the spring forces exerted by the coiled springs 143 on the winding
drums 142 can counterbalance the weight applied on the second rail
104, the resistance generated by the resistance balancing units 110
and other internal frictional forces to stop the winding drums 142.
Owing to the balance of all the forces applied thereon, the second
rail 104 can be kept stationary at the desired position in a stable
manner.
[0050] With the aforementioned construction, the second rail 104
can be held stationary at any position. Even if the second rail 104
is adjusted to reach a limit of the working range of the coiled
springs 143, the resistance balancing units 110 can still create
proper resistance that can balance the spring force of the cord
winding unit 112 such that the operation of the window shade 100
can be facilitated, and the second rail 104 kept be stationary in
an equilibrium condition at any heights. Aside the aforementioned
embodiments, the resistance balancing unit can also be associated
with other constructions of the cord winding unit.
[0051] FIG. 13 is a schematic view illustrating another embodiment
associating a resistance balancing unit 210 with a cord winding
unit 212, and FIG. 14 is a schematic view detailing the
construction of the cord winding unit 212. As shown in FIG. 13, the
resistance balancing unit 210 can be associated with the cord
winding unit 212 to form a control module. The resistance balancing
unit 210 can be similar in construction to the resistance balancing
unit 110 of the previous embodiment, including a housing 214, a
rotary pulley 216 and a torsion spring 218. The pulley 216 can be
pivotally assembled with the housing 214, and can include a winding
portion 216A and a shaft extension 216B. The shaft extension 216B
can project from a side of the winding portion 216A along a same
axis of rotation.
[0052] The torsion spring 218 can be tightly mounted on an outer
peripheral surface of the shaft extension 216B. Two protruding ends
218A and 218B of the torsion spring 218 can be respectively
disposed adjacent to two abuttal surfaces 232 of the housing
214.
[0053] The suspension cord 108 can enter the resistance balancing
unit 210 from a first face thereof, wrap about one and half turn
around the winding portion 216A, and extend outward from a second
face of the resistance balancing unit 210. Accordingly, a first
portion of the suspension cord 108 outwardly adjacent to the first
face of the resistance balancing unit 210 can extend in a direction
different from a second portion of the suspension cord 108
outwardly adjacent to the second face of the resistance balancing
unit 210.
[0054] Referring to FIGS. 13 and 14, the cord winding unit 212 can
include a casing 240. A side of the casing 240 can be provided with
an extending plate 240A for affixing the resistance balancing unit
210. The suspension cord 108 can pass through the resistance
balancing unit 210, and then travel into the casing 240 via a hole
242 to connect with one or more part inside the cord winding unit
212.
[0055] As shown in FIG. 14, the cord winding unit 212 can include a
winding drum 244 and a coiled spring 246 mounted inside the casing
240. A side of the winding drum 244 can be connected with a hollow
shaft portion 248. The winding drum 244 and the shaft portion 248
can be formed integral in a single body, or can be separate parts
assembled together. The casing 240 can have an interior in which
are defined a first receiving space 240B and a second receiving
space 240C. The winding drum 244 can be disposed in the first
receiving space 240B, and the shaft portion 248 can be disposed in
the second receiving space 240C, such that the winding drum 244 and
the shaft portion 248 can rotate about a same axis relative to the
casing 240. Moreover, when the cord winding unit 212 is assembled
with a window shade, a transmission axle 310 (shown with dotted
lines) can pass through the winding drum 244 and the shaft portion
248, whereby multiple cord winding units can be driven concurrently
via the transmission axle 310.
[0056] The coiled spring 246 can be installed around the shaft
portion 248 in the second receiving space 240C. The coiled spring
246 can have a first end connected with the shaft portion 248, and
a second end connected with the casing 240.
[0057] The suspension cord 108 can travel through the hole 242, and
extend into the first receiving space 240B to connect with the
winding drum 244. The winding drum 244 can be biased in rotation by
the coiled spring 246 for winding the suspension cord 108.
[0058] In conjunction with FIGS. 13 and 14, FIG. 15 is a schematic
view illustrating a window shade 300 provided with the resistance
balancing unit 210 and the cord winding unit 212. The window shade
300 can include a first rail 302, a second rail 304 provided with
the resistance balancing unit 210 and the cord winding unit 212,
and a shading structure 306 connected between the first and second
rails 302 and 304. The second rail 304 can be affixed with a top of
a window frame, and the first rail 302 can be suspended vertically
from the second rail 304.
[0059] The second rail 304 can include a transmission axle 310, and
a plurality of resistance balancing units 210 and cord winding
units 212. The transmission axle 310 can be assembled through the
casing 240, the shaft portion 248 and the winding drum 244 of each
cord winding unit 212, and thereby define a same axis of rotation
about which the shaft portions 248 and the winding drums 244 of the
cord winding units 212 can rotate in unison.
[0060] The suspension cords 108 (shown with dotted lines) can be
respectively connected between the cord winding units 212 and the
first rail 302. More specifically, each of the suspension cords 108
can have a first end connected with the winding drum 244 of one
cord winding unit 212, and a second end securely affixed with the
first rail 302.
[0061] Like the embodiments previously described, when the first
rail 302 is lowered, each suspension cord 108 can unwind from the
associated winding drum 244 which is driven in rotation. As it
unwinds from the winding drum 244, the suspension cord 108 can
drive the pulley 216 in rotation, which causes the end 218A of the
torsion spring 218 to push against the abuttal surface 232. As a
result, the torsion spring 218 previously in a tightened state can
loosen, such that the pulley 216 can rotate relative to the torsion
spring 218. When the user stops lowering the first rail 302, the
torsion spring 218 can recover its tightened state on the pulley
216. As a result, the pulley 216 no longer rotates, and the
increased contact area between the suspension cord 108 and the
pulley 216 can create frictional resistance. Accordingly, the total
spring force exerted by the coiled springs 246 on the winding drums
244 can counterbalance the weight applied on the first rail 302,
the resistance created by the resistance balancing units 210, and
frictional forces exerted by other internal parts. The winding
drums 244 can thereby stop rotating, and the first rail 302 can be
sustained at the desired height in equilibrium.
[0062] As shown in FIG. 16, when the first rail 302 is raised, the
suspension cords 108 between the first rail 302 and the second rail
304 can become loose (i.e., form a slack). Accordingly, the winding
drum 244 of each cord winding unit 212 can reversely rotate to wind
the associated suspension cord 108. When the user stops raising the
first rail 302, the torsion springs 218 can respectively tighten on
the pulleys 216. As a result, each of the pulleys 216 can stop
rotating, and the increased contact area between each suspension
cord 108 and the associated pulley 216 can create frictional
resistance. Accordingly, the total spring force exerted by the
coiled springs 246 on the winding drums 244 can counterbalance the
weight applied on the first rail 302, the resistance created by the
resistance balancing units 210, and frictional forces exerted by
other internal parts. The winding drums 244 can thereby stop
rotating, and the first rail 302 can be sustained at the desired
height in equilibrium.
[0063] The resistance balancing units described previously can also
be implemented with other constructions. For example, while the
resistance balancing unit has been described as using a
bidirectional torsion spring, other embodiments of the resistance
balancing unit can also use a unidirectional torsion spring. A
variant embodiment of the resistance balancing unit is exemplary
described hereafter with reference to FIGS. 17 and 18.
[0064] FIG. 17 is a cross-sectional view illustrating another
construction of a resistance balancing unit 410, and FIG. 18 is a
bottom view of the resistance balancing unit 410. The resistance
balancing unit 410 can be similar to the previous embodiment in
construction, including a housing 414, a pulley 416, a torsion
spring 418 and a movable blade 420. The pulley 416 can be pivotally
assembled with the housing 414, and can include a winding portion
416A and a shaft extension 416B. The shaft extension 416B can
project from a side of the winding portion 416A along a same axis
of rotation. The torsion spring 418 can be a unidirectional torsion
spring having an end 418A. The torsion spring 418 can be tightly
mounted on an outer peripheral surface of the shaft extension 416B,
and the end 418A can be anchored with the housing 414. The
suspension cord 108 can enter the resistance balancing unit 410
from a first face 414A, wrap about one and half turn around the
winding portion 416A, travel past the blade 420, and extend outward
from a second face 414B of the resistance balancing unit 410.
[0065] The operation of the resistance balancing unit 410 can be
similar to the previous embodiments. When the second rail (i.e.,
the rail suspended from the first rail) is lowered, each stretched
suspension cord 108 can drive rotation of the associated pulley
416, which causes the torsion spring 418 previously tightening on
the pulley 416 to loosen. Accordingly, the pulleys 416 can
respectively rotate relative to the torsion springs 418, and the
suspension cords 108 extending between the first and second rails
can lengthen. When the user stops lowering the second rail (i.e.,
the first and second rails become stationary), the torsion springs
418 can respectively tighten on the pulleys 416. As a result, the
pulleys 416 stop rotating, and the wrap of the suspension cords 108
around the pulleys 416 can create frictional resistance, which can
act to balance all of the forces exerted on the second rail.
Accordingly, the second rail can be sustained at the desired
position in equilibrium.
[0066] While the aforementioned embodiment has the resistance
balancing unit arranged at a turn position of the suspension cord
108, it will be appreciated that the resistance balancing unit can
also be used at other locations. For example, as shown in FIG. 19,
the suspension cord 108 can turn around the a pulley 502, enter the
resistance balancing unit 510 from a first face 514A thereof, wrap
about one turn around the pulley 516, travel past the movable blade
520, exit the resistance balancing unit 510 via a second face 514B
thereof, and then connect with the cord winding unit 112/212. Like
previously described, the resistance balancing unit 510 can include
a torsion spring tightly mounted around the pulley 516 (not shown).
The second side 514B and the first side 514A can be substantially
parallel to each other, such that the portions of the suspension
cord 108 respectively entering and exiting the resistance balancing
unit 510 can be parallel to a same direction.
[0067] The window shades described herein do not have any operating
cords, and can be conveniently adjusted by raising and lowering the
lower rail. Accordingly, the risk of children strangling on
operating cords from the window shade can be prevented. Moreover,
the assembly of the resistance balancing unit can allow to
accurately hold the shading structure in equilibrium at any
heights.
[0068] Realizations in accordance with the present invention
therefore have been described only in the context of particular
embodiments. These embodiments are meant to be illustrative and not
limiting. Many variations, modifications, additions, and
improvements are possible. Accordingly, plural instances may be
provided for components described herein as a single instance.
Structures and functionality presented as discrete components in
the exemplary configurations may be implemented as a combined
structure or component. These and other variations, modifications,
additions, and improvements may fall within the scope of the
invention as defined in the claims that follow.
* * * * *