Note: Descriptions are shown in the official language in which they were submitted.
CA 02332702 2001-O1-29
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1 BRIEF DESCRIPTION Ol-~ ~I~I-I1DRAWINGS
2 Fig. I is an operational front plan view of a cordless venetian blind with a
lifting
3 mechanism in accordance with the present invention;
4 Fig. 2 is a partially exploded perspective view in partial section of the
lifting
mechanism for the cordless venetian blind in Fig. l;
6 Fig. 3 is an exploded perspective view of the lifting mechanism in Fig. 2
for a
7 cordless venetian blind;
8 Fig. 4 is a front cross sectional front plan view of the lifting mechanism
for a
9 cordless venetian blind along line 4-4 in E'ig. 2;
Fig. 5 is side cross sectional view of another embodiment of the brake plate
of the
11 lifting mechanism for a cordless venetian blind in accordance with the
present invention;
12 and
13 Fig. 6 is a top plan view of another embodiment of the lifting mechanism
for a
14 cordless venetian blind in accordance with the present invention.
BACKGROUND OF rfI-IE fNVEN~I'I~N
16 1. Field of the Invention
17 The present invention relates to a lifting mechanism, and more particularly
to a
18 lifting mechanism for a cordless venetian blind.
19 2. Description of Related Art
A conventional lifting mechanism for a cordless venetian blind in accordance
with
21 the prior comprises a hollow frame mounted on the wall above the window. A
series of
22 slats parallel to the frame are mounted below the frame by two cords
respectively attached
23 to opposite ends of the lowest blind. A rotor moves the series of slats
from a horizontal
24 position to a nearly vertical position to selectively open and close the
slats with respect to
CA 02332702 2001-O1-29
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1 the passage of light. A control device is mounted in the frame and has a
cord with one end
2 attached to the lowest blind and the other passing through the control
device for a user to
3 pull to open or close the venetian blind. It is an inconvenient design
because the user's
4 hand must carry the weight of all of the slats when opening the conventional
venetian
blind.
6 The present invention has arisen to mitigate and/or obviate the
disadvantages of
7 the conventional venetian blind.
8 SUMMARY OF THE INVENTION
9 The main objective of the present invention is to provide an improved
lifting
mechanism for a cordless venetian blind that makes the opening or closing of
the venetian
11 blind easier and more convenient.
12 The lifting mechanism comprises a bracket to hold the lifting mechanism.
Two
13 rollers are respectively rotatably mounted in the bracket. A balance wheel
set is mounted in
14 the bracket and includes a first wheel rotatably mounted between the two
rollers and
simultaneously rotated with the two rollers, and a second wheel rotatably
mounted in the
1 G bracket near the first wheel. An S-shaped constant force motor spring is
mounted between
17 the first wheel and the second wheel, and has a first end attached to a
periphery of the first
18 wheel and a second end wound on the second wheel. Due to the constant force
motor
19 spring, the cord is unnecessary and the cordless venetian blind can be
opened or closed
easily.
21 Further benefits and advantages of the present invention will become
apparent
22 after a careful reading of the detailed description with appropriate
reference to the
23 accompanying drawings.
24 D>~TAI D DF RIPTION I~ THIi INVENTION
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With reference to the drawings and initially to Figs. 1 and 2, a cordless
venetian
2 blind usually comprises a frame ( 10) securely attached to the wall, a rotor
(20) mounted in
3 the frame (10) and a lifting mechanism (30) mounted in the frame (10). The
frame (10)
4 includes a series of slats (11) each parallel to the frame (10) and mounted
below the frame
( 10) by two balance cords ( 12) respectively attached to opposite ends of the
lowest blind.
6 The rotor (20) moves the series of slats ( 11) from a horizontal position to
a nearly vertical
7 position to selectively open and close the slats (11) with respect to the
passage of light. The
8 rotor (20) is a well-known structure so it will not be described in detail.
9 The lifting mechanism (30) is mounted in a U-shaped bracket (34) that is
attached
to the frame (10). The lifting mechanism (30) includes two concentric rollers
(31) and a
11 balance wheel set (32) each rotatably mounted in the bracket (34). The
balance wheel set
12 (32) includes a first wheel (321) concentrically mounted between the two
rollers (31) and
13 simultaneously rotated with the two rollers (31 ), and a second wheel (322)
rotatably
14 mounted to correspond to the First wheel (321 ). An S-shaped constant force
motor spring
(33) is coupled between the first wheel (321) and the second wheel (322).
16 With reference to Digs. 2 and 3, in the preferred embodiment of the present
17 invention, the first wheel (321) and the two rollers (31) are integral. The
first wheel (321)
18 has a diameter smaller than that of the two rollers (31 ). A first hole
(310) is axially defined
19 in the rollers (31 ) and extends through the first wheel (321 ). A first
axle (311 ) is securely
mounted in the first hole (310), and a i7rst through hole (312) is axially
defined in the first
21 axle (311 ). A f rst axle pin (313) extends through the first through hole
(312) and has two
22 ends respectively held by opposite sidewalk of the bracket (34). A second
hole (323) is
23 axially defined in the second wheel (322). A second axle (324) is securely
mounted in the
24 second hole (323), and a second through hole (325) is axially defined in
the second axle
CA 02332702 2001-O1-29
(324). A second axle pin (326) extends through the second through hole (325)
and has two
2 ends respectively held by opposite sidewalk of the bracket (34). The
constant force motor
3 spring (33) includes a strip which has a specific width and a specific
thickness and has a
4 connector (331) formed on one end attached to the periphery of the first
wheel (321 ). The
S connector-(331 ) includes a neck (332) formed near the end to be engaged in
a slot (327)
6 that is circumferentially defined in the periphery of the first wheel (321 )
to hold the
7 constant force motor spring (33) in place.
8 The bracket (34) includes a bottom (340), two sidewalls and an inverted U-
shaped
9 cover (35) attached to the top portions of the two sidewalls to form a
passage for receiving
the lifting mechanism in the passage. The sidewall of the bracket (34) has two
third through
11 holes (341) respectively defined to hold the first axle pin (313) and the
second axle pin
12 (326). The axle pins (313, 326) in the preferred embodiment of the present
invention are
13 rivets. It further can be a pin, a bolt with a nut or the like. Multiple
ribs (342) extending
14 laterally out from each sidewall of the bracket (34), and a hooked lip
(350) is formed
laterally inward on the end ol'each sidewall of the cover (35). The hooked lip
(350)
16 engages the rib (342) of the bracket (34) to hold the cover (35) in place.
The bottom (340)
17 of the bracket (34) includes two ends each having a tongue (343) extending
from the end of
18 the bottom (340). The tongue (343) has a bore (344) defined to allow an
attachment
19 member (345) to extend through the tongue (343) to attach the bracket to
the frame (10).
The attachment member (345) is a rivet, a self=threading screw or a bolt with
a nut.
21 With reference to I~igs. 1 and 4, in operation, the roller (31) will fully
wind the
22 balance cord (12) when the slats (11) are lifted toward the frame (10).
Moreover, most of
23 the motor spring (33) is wound on the second wheel (322) and only enough of
the motor
24 spring (33) is wound on the Iirst wheel (321) to attach the end of the
spring (33) and to
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1 provide the desired holding force. The slats (I l) are separated from one
another when they
2 are in the lowered position and the balance cord (12) is unwound from the
roller (31). Then
3 the slats (11) will be respectively suspended from straps (not shown) which
are attached to
4 the frame ( 10) and controlled by the rotor (20), so that the weight of all
the slats ( 11 ) does
not bear by the constant force motor spring (33). Consequently, with the slats
(11) lowered,
6 the motor spring (33) is substantially transferred from the second wheel
(322) to the first
7 wheel (321 ), thereby decreasing the amount of force exerted on the slats (
11 ). Therefore,
8 the reduced spring Force prevents the slats (l l) from self lilting.
9 When opening the cordless venetian blind, the slats (11) are lifted toward
the frame
( 10), resulting in a spring driven rotation of the roller to wind up the
balance cord ( 12). The
11 motor spring (;33) will wind back onto the second wheel (322), with a
continually
12 increasing force as the weight of the slats ( 11 ) and accumulating slats (
11 ) continues to
13 increase. The operation is finished when the Fig. 1 configuration is
achieved.
14 With reference to Fig. 3 and 4, a brake plate (351 ) has one end attached
to the top
portion of the cover (35) and the other pressing the outer periphery of the
roller (31) to
16 prevent the first wheel (321 ) (i~om sell=reversing. An adjusting bolt
(352) is screwed
17 through the cover (35) to press the brake plate (351) and adjust the
pressure between the
18 brake plate (352) and the roller (31).
19 With reference to 11 ig. 5, another embodiment of the brake plate (353) has
one end
attached to the cover (35) ~~nd the other extending to abut the side of the
roller (31). The
21 brake plate (353) applies a side force to the roller (31) to prevent the
roller (31) from
22 reversing too speedily.
23 With reference to Fig. 6, another embodiment of the lifting mechanism (40)
in
24 accordance with the present invention leas two rotors (20) respectively
mounted in opposite
CA 02332702 2001-O1-29
1 ends of the frame (10). An axle (21) connects the two rotors (20). The
lifting mechanism
2 (40) includes two rollers (41) and a balance wheel set (42). The balance
wheel set (42)
3 includes a first wheel (421 ) co-axially mounted between the two rollers (41
). The axle (21 )
4 passes through the center of a hollow axle (43) that axially extends through
the first wheel
(421 ). The two rollers (4 I ) are respectively attached to opposite ends of
the hollow axle
6 (43). The balance wheel set (42) includes a second wheel (422) mounted near
the first
7 wheel (421 ) and a constant force motor spring (44) mounted between the
first wheel (421 )
8 and the second wheel (422). 'hhe motor spring (44) has one end attached the
first wheel
9 (421 ) and the other wound on the second wheel (422). The operation of the
embodiment is
the same as the previously described prel-erred embodiment.
1 I Although the invention has been explained in relation to its preferred
embodiment,
12 it is to be understood that many other possible modifications and
variations can be made
13 without departing from the spirit and scope of the invention as hereinafter
claimed.
