Cordless blind with variable displacement resistance comprises spring control connected to blind window covering and variable friction mechanisms introduced when required

The present invention relates generally to window coverings, and more particularly relates to blinds and sun shades without cords.

There are different window coverings, including retractable sun shades and venetian blinds. In conventional venetian blinds, a plurality of slats are supported in ladder cords which extend between an upper track and a lower track. One or more coil cords extend from the bottom rail, through the slats, and out of the top rail. An upward force exerted on the winding cords lifts the lower rail to the upper rail, tightening the slats from lower to higher.

In such blinds, the winding cords are operated manually. More specifically, the winding cords which extend from the bottom rail, through the slats, and out of the top rail are pulled by a user who thereby lifts the bottom rail, and hence the slats. Typically a latch is provided for securing the reel cord so that the blinds can be secured in various positions between an extended down position and a fully retracted raised position.

More recently, in cordless blind products, a spring drive has been provided which is coupled to a winding drum to which the winding cord is attached. The spring-loaded actuator provides lifting force to the reel cord. Such spring controls provide smooth operation of the shade, and prevent very long cords extending from the shade, which can be unsightly and can become tangled, thereby preventing operation of the shade.

With a cordless blind product, it is difficult to balance the force of the spring drive. When the blind is extended, the slats are supported by the ladder cords, and the weight supported by the spring drive is reduced. Conversely, when the awning is retracted, the spring drive must support the weight of the bottom rail and all slats. Unless a spring drive provides a corresponding variable force, many problems can arise. For example, if the spring drive does not provide sufficient lifting force, the awning cannot stay in the fully retracted position, and it will fall slowly. If the spring drive provides too much lifting force, the shade cannot stay at the extended position, and the shade may slowly pucker upward.

In practice, one can use constant force spring drives sized to support the full intended weight of the slats, and an external mechanism, such as a clutch, to lock the spring drive when the awning is level with the location. desired. However, such devices do not provide smooth operation.

Variable force spring controls have therefore been developed which have made it possible to extend the blind virtually to any position from the fully retracted position to the fully extended position. However, the sizing of the spring drive is difficult. The variable force can be created by using a spring element beveled in width, thickness and / or diameter, thus resulting in a force curve having its greatest force when the awning is retracted, and its force the most. lower when the awning is extended. Depending on the size and weight of the slats and bottom rail, the spring drive may be sized accordingly, or multiple spring drives may be used.

Even with such variable force spring drives, it may be advantageous to introduce friction into the system. Such additional friction creates a wider acceptable operating range for a given size of spring drive. However, if too much friction is added to the system, the operation of the spring control and the blind will not be smooth. In addition, it is desirable to add friction only when the shade is retracted, and it is desirable that little or no additional friction is added when the shade is extended.

According to a first aspect of the present invention, there is provided a window sunshade which has an expandable cover, the cover being movable in a first direction as it expands to cover a window, the cover being movable. in a second direction when retracting away from the window, a spring drive operatively connected to the cover expandable to move the cover in the second direction, a rotary output connected to the spring drive, and a retarder associated with the rotary output, the retarder introducing resistance against movement of the overlap in the second direction, while not introducing resistance against displacement of the overlap in the first direction.

According to other aspects of the present invention, the retarder comprises a bearing or a one-way brake.

According to another aspect of the present invention, there is provided a blind which has an expandable cover, the cover being movable in a first direction when it is enlarged, and in a second direction when it is retracted, a cord. connected to the expandable cover, the cord being movable in a first direction when the cover is retracted and in a second direction as the cover expands, a spring drive connected to the bead to move the cover between the retracted position and the enlarged position, and a one-way roller which cooperates with the bead to add resistance against movement of the bead in the first direction.

According to another aspect of the present invention, there is provided a blind having an expandable cover, the cover being movable in a first direction when it is enlarged and in a second direction when it is retracted, a cord connected to the. expandable cover, a cord spool connected to the cord, a spring drive connected to the cord spool via a rotating shaft, and a brake adapted to impart a first force against the shaft when the expandable cover moves in the first direction, and a second, higher force, when the expandable cover moves in the second direction.

According to yet another aspect of the present invention, there is provided a spring drive assembly which includes a frame, a winding drum pivotally mounted on the frame, a drive drum pivotably mounted on the frame, a drive drum pivotally mounted on the frame, a drive drum pivotally mounted on the frame, a drive drum pivotally mounted on the frame coil spring interconnected between the winding drum and the drive drum, a rotary member operably connected to the drive drum, and a retarder associated with the rotating element. The retarder introduces resistance to the rotating member in a first direction of rotation, but not in a second direction of rotation.

These and other aspects and features of the present invention will become more apparent from the following detailed description, made with reference to the accompanying drawings, in which:

- Figure 1 is a front view of a blind according to the present invention,

- Figure 2 is a top view of Figure 1,

- Figure 3 is a partial view on a larger scale of Figure 1,

- Figure 4 is a sectional view taken along line 4-4 of Figure 3,

- Figure 5 is a sectional view of a first embodiment of a unidirectional bearing according to the present invention,

- Figure 6 is a sectional view of a second embodiment of a unidirectional bearing according to the present invention,

- Figure 7 is a schematic representation of a second embodiment of the present invention,

- Figure 8 is a schematic representation of a third embodiment of the present invention,

- Figure 9 is a schematic representation of a fourth embodiment of the present invention,

- Figure 10 is a schematic representation of a fifth embodiment of the present invention,

- Figure 11 is a schematic representation of a sixth embodiment of the present invention,

- Figure 12 is a schematic representation of a seventh embodiment of the present invention,

- Figure 13 is a schematic representation of an eighth embodiment of the present invention, and

- Figure 14 is a schematic representation of a ninth embodiment of the present invention.

Although the present invention is susceptible to various modifications and alternative constructions, certain representative embodiments thereof have been shown in the drawings, and they will be described below in detail. It should be understood, however, that there is no intention to limit the present invention to the specific forms disclosed but on the contrary that the intention is to cover all modifications, alternative constructions and the like falling within the spirit and the imagination. scope of the present invention as defined by the appended claims.

Reference is now made to the drawings and in particular to FIG. 1, in which a blind or sun visor in accordance with the present invention is generally indicated by the numeral 20. As shown therein, the blind 20 comprises a top rail 22, a bottom rail 24, and window covering material 26 located therebetween. In the illustrated embodiment, the window covering 26 has a plurality of slats 28, but other materials, fabrics and structures can be used.

To raise and lower the lower rail 24 and the slats 28, and thus move the blind 20 between a retracted upper position and a lowered extended position, the slats 28 are supported by first and second ladder cords forming a series of continuous loops. (not shown), and first and second coil cords 30, 32 extend through slats 28 and connect base rail 24 to first and second cord spools 34 and 36. The rotation of the first and second cord spools 34 and 36 winds and unwinds the first and second winding cords 30, 32 respectively, and thus raises and lowers the blind 20. As opposed to the usual venetian blinds which extend the winding cords. from the top rail 22 to manually raise and lower the blind 20, a cordless blind as described has a spring drive 38 to provide the driving force to raise the blind 20.

More specifically, as shown in Fig. 2, the spring drive 38 comprises a winding drum 40 and a drive drum 42 which are connected by an elastic member 44. The elastic member 44 is a coil spring having in the form of a strip of metal prestressed on a first side, thereby causing the elastic member 44 to be natural or relaxed in the form of a wound coil. The elastic member 44 is wound on the winding drum 40 in its relaxed state, and is connected to the driving drum 42, so that during a rotation of the driving drum 42, the elastic member 44 is wound up. back onto the drive drum 42. Thus, as the drive drum 42 rotates and winds back the elastic member 44 onto the drive drum, the elastic member 44 is biased to rewind back onto the take-up drum 40. C ' is that restoring force that blind 20 uses to raise window covering 26.

Referring now to Figures 2 and 3, the spring drive 38 is shown positioned between the first and second cord spools 34 and 36. Cord spools 34 and 36 mesh mutually, through gears, with winding drum 40 and drive drum 42, so that rotation of cord spools 34 and 36 causes rotation. of the drive drum 42 and of the winding drum 40, and therefore a winding or unwinding movement of the elastic element 44.

For example, when moving the blind 20 from the retracted position to the extended position, the lower rail 24 is pulled away from the upper rail 22. This in turn pulls the first and second winding cords 30 and 32 away. of the upper rail, and causes the rotation of the cord reels 34 and 36. The rotation of the first and second cord spools 34 and 36 in turn causes a rotation of the drive drum 42, and thus backwind the elastic member from the winding drum 40 to the drive drum 42. The winding drum 40 is mounted independently, such that a rotation of the first and second cord spools 34 and 36 does not directly cause a rotation of the winding drum 40.

Thus, by pulling the lower rail 24 downward away from the upper rail 22, an elastic member 44 is wound back onto the drive drum 42, creating a restoring force which tends to drive the elastic member 44 to s 'winding back onto the winding drum 40, and thus pulling the lower rail towards the upper rail. By appropriately dimensioning the width, thickness and / or diameter of the elastic member 44, this restoring force can be calibrated so that it is greatest when the lower rail is fully retracted, and the lower when the bottom rail is fully extended. Otherwise, if a constant force elastic member 44 is used, a locking mechanism or a clamping mechanism must be used.

To ensure that the resilient member 44 does not cause unwanted movement of the blind 20, additional friction is added to the system of the present invention, through various forms of variable friction mechanisms or retarders. In the following description which corresponds to Figures 4 to 14, various embodiments are described to show multiple ways by which friction can be added to the system in a first direction of movement of the awning 20, and not in the direction of movement. opposite direction. However, it should be understood that these embodiments are listed by way of example only, and are not exclusive.

Referring first to Figures 2-4, the first cord 30 is shown extending from the first spool of cord 34 and wound around a capstan 46. The cord 30 sec. 'extends back in the direction of the first spool of cord 34, and then downward through a cord mount 47 mounted on the upper rail 22. The capstan 46 has a cylindrical hub 48 with first and second bevelled sections or truncated 50 and 52. The capstan 46 also has a through hole 54 around which the capstan 46 can rotate. As shown in Figure 4, the capstan 46 is mounted on a frame 56 through an axle 58 and a bearing 60. A second capstan 46, for the second bead 32, is similarly arranged.

Bearing 60 is a one-way style bearing, in that it spins freely in a first direction (clockwise or counterclockwise), but it resists being rotated in the opposite direction. By wrapping the first winding cord 30 around the capstan 46, and arranging the one-way bearing 60 in an orientation in which it rotates freely with the cord 30 when the lower rail 24 is pulled from the upper rail 22, the capstan 46 will necessarily resist a rotation in the imposed direction. This means that friction will be introduced, via the one-way bearing 60, when the lower rail 24 is moved towards the upper rail 22. Since the capstan 46 will not rotate, the frictional resistance between the first bead d winding 30 and the cylindrical hub 48 of the capstan 46 will slow down the movement of the first winding cord 30, and therefore the movement of the blind 20.

Figures 5 and 6 show two embodiments of the unidirectional bearings which can be used in the present invention. However, again, such embodiments are given by way of example only, and are not exclusive. Referring to Figure 5, one-way bearing 60 is shown as having an outer race 62 having a plurality of locking ramps 64 which correspond in number to the number of balls 66 journalled within a raceway. interior 68. The outer race 62 is frictionally engaged within the through hole 54 of the capstan 46, so that relative rotation between the outer race 62 and the capstan 46 is not possible. If capstan 46 is rotated clockwise as shown in Fig. 5, balls 66 likewise rotate clockwise, while axle 58 is stationary. If the capstan 46 attempts to rotate counterclockwise, the balls 66 are frictionally engaged with the locking ramps 64 to prevent such rotation.

Referring to Figure 6, another type of one-way bearing 60 is shown. The bearing 60 has an outer race 70 frictionally engaged with the through hole 54 of the capstan 46. A plurality of locking tabs 72 extend radially inward from the outer race 70. Axle 58 shown in Figure 6 is stationary, but has a star-shaped cross section formed by a plurality of cam surfaces 74 extending radially outwardly therefrom. More specifically, each cam surface 74 has an arched portion 76 and a locking shoulder 78. When the capstan 46 and the outer raceway 70 rotate clockwise, the arched portions 76 come into contact with the flexible locking tabs 72 by pushing the locking tabs 72 outward, and allowing capstan 46 to rotate. However, when capstan 46 and outer race 70 attempt to rotate counterclockwise, locking tabs 72 contact locking shoulders 78, and prevent rotation.

Figure 7 shows a second embodiment of the present invention in which the cord spool 34 is not linearly aligned with the spring drive 38, but rather is connected to a rotation shaft 80 extending from it. of the spring drive 38. A roller 82 is arranged downstream of the cord reel 34, and is mounted on a one-way bearing 60. Roller 82 is allowed to rotate clockwise, but not counterclockwise.

Fig. 8 is a schematic representation of a third embodiment of the present invention in which the roller 82 is mounted on a tension spring 84. Again, the roller 82 is located downstream of the cord spool 84, and the roller 82 is mounted on a one-way bearing 60. The tension spring 84 adds additional friction to the movement of the winding cord 30.

Fig. 9 is a schematic representation of a fourth embodiment of the present invention in which a second roller 86 mounted on a second tension spring 88 is disposed so as to be opposed to the first roller 82. The first and second rollers 82 and 86 are downstream of cord reel 34, and are mounted on one-way bearings 60. The first and second tension springs 84 and 88 clamp the cord between the first and second rollers 82 and 86 to add additional friction to the movement of the winding cord 30.

Figures 10 and 11 show fifth and sixth embodiments, in which resistance is added against the rotation of shaft 80, as opposed to winding cord 30. More specifically, in the figure 10, a brake arm 90 is disposed at an angle to the shaft 80. The brake arm 90 has a cam surface 92 and a brake surface 94. The brake arm 90 is urged into contact with the shaft 80 by a tension spring 96. As the shaft 80 rotates clockwise as shown in Fig. 10, the shaft 80 comes into contact. with the cam surface 92, and pushes the brake arm 90 away by pushing against the force of the tension spring 96. However, when the shaft 80 attempts to rotate counterclockwise, as shown in Fig. 10, the tension spring 96 pushes the braking surface 94 into contact with the shaft 80, and therefore resists. to one rotation.

Figure 11 is similar to Figure 10 in that a brake arm 90 is used, the embodiment of Figure 11 however including three brake arms 90, all of which are mounted on the shaft 80. In addition, , the shaft 80 and the brake arms 90 are mounted inside a cylinder 98. The brake arms 90 are pivotally attached to the shaft 80 at pivots 100, so that rotation of the shaft 80, counterclockwise, will cause the surfaces of the brake to be rotated. cam 92 to contact the cylinder 98 and urge the brake arms 90 radially inwardly towards the shaft 80. As a result, the rotation of the shaft 80 will not be obstructed. However, if the shaft 80 attempts to rotate clockwise, the braking surfaces 94 of the brake arms 90 contact the cylinder 98, and resist rotation of the shaft 80. .

Fig. 12 shows a seventh embodiment of the present invention in which a first roller 102, having a fixed pivot 104, is arranged adjacent to a second roller 106 mounted on a tension spring 108. The winding cord 30 is driven. around the second roll 106 between the first roll 102 and the second roll 106. If the winding cord 30 is pulled down, the tension spring 108 compresses, moving the cord 30 out of cooperation with the first roller 102. The first roller 102 can thus rotate with little friction being added to the movement. winding cord 30. However, as the coil cord 30 attempts to move upward, the tension spring 108 urges the coil cord 30 into pinch engagement between the first and second rollers 102 and 106, thereby adding friction and pressure. resistance to winding cord movement 30.

Figures 13 and 14 show eighth and ninth embodiments of the present invention, in which first and second pulleys 110 and 112 are mounted outside the spring drive 38 with a belt 114 being driven around the first and second pulleys. second pulleys 110 and 112.

In Fig. 13, the first and second pulleys are mounted concentric with the first and second cord spools 34 and 36, the first pulley 110 being mounted on a one-way bearing 60. It should be understood that, alternatively, the second pulley 60 can be mounted on a unidirectional bearing. As a result, the one-way bearing 60 does not obstruct the rotation of the cord spools in a first direction, while the one-way bearing 60 impedes the rotation of the cord spools 34 and 36 in the opposite direction.

Figure 14 is similar to Figure 13, at

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As can be appreciated from Fig. 14, the roller 118 can move on an arc path 122 when the pivot arm 120 pivots on the arc path 122. By doing so, the diameter can be increased or decreased. belt 114, and thus increase or decrease the tension of belt 114. Belt tension adjustment mechanism 116 adds a constant amount of friction to belt 114 regardless of the direction of rotation of belt 114. As a result, at least one of the pulleys 110 and 112 is mounted on a one-way bearing 60.

From the above, it can therefore be seen that the present invention provides a spring drive, and a window shade driven by a spring drive, having a mechanism for adding resistance to setting. rotation of the spring drive in a first direction, and not in the opposite direction.