Patent Description:
A window treatment may be mounted in front of one or more windows, for example to prevent sunlight from entering a space and/or to provide privacy. Window treatments may include, for example, roller shades, roman shades, venetian blinds, or draperies. A roller shade typically includes a flexible shade fabric wound onto an elongated roller tube. Such a roller shade may include a weighted hembar located at a lower end of the shade fabric. The hembar may cause the shade fabric to hang in front of one or more windows over which the roller shade is mounted. A typical window treatment may be mounted to a structure surrounding a window, such as a window frame. Such a window treatment may include brackets at opposed ends thereof. The brackets may be configured to operably support a roller tube, such that a flexible material may be raised and lowered. For example, the brackets may be configured to support respective ends of the roller tube. The brackets may be attached to a structure, such as a wall, ceiling, window frame, or other structure. <CIT> discloses a brake assembly for a window treatment wherein the assembly comprises a brake spring comprising a plurality of coils and first and second tangs extending from either end of this plurality of coils. The tangs show an L-shape which is twisted perpendicular relative to the radial direction of the coil.

The invention is defined by independent claim <NUM>; other aspects of the invention are defined in the dependent claims. Described herein are brake assemblies for window treatments employing motorized roller tube systems. Motorized roller tube systems may include a roller tube for winding (and unwinding) a flexible member, such as a shade fabric. A housing may be disposed in the roller tube and retains a motor, logical controls for the motor, a drive shaft for rotating a puck connected to the roller tube via a puck shaft, and a brake assembly. The motor may use AC power or DC power. Power may be supplied by wire or by battery. A brake assembly includes a mandrel, an input member coupled to the drive shaft and rotatable around the mandrel, an output member coupled to the puck shaft and rotatable around the mandrel, and a brake spring disposed upon the mandrel. A brake spring described herein comprises a plurality of coils, a tang extending from the plurality of coils, and a support portion extending from the tang, wherein when the motor is not actuated, the brake assembly prevents the flexible member from coming unwound.

Another brake assembly for a motorized roller tube system includes a mandrel and a brake spring disposed upon the mandrel, the brake spring comprising a plurality of coils, a tang extending from the plurality of coils, and a support portion extending from the tang, wherein, in a first rotational position, a force is exerted on the tang, thereby back driving the spring, causing the plurality of coils to tighten on the mandrel and prevent rotation therebetween.

A brake spring for a motorized roller tube system includes a plurality of coils having a tang assembly at either end, each tang assembly comprising a radially extending tang and a support portion extending from the tang. The tang receives several forces acting thereupon to affect a tension of the plurality of coils. For example, the tang may be acted on by a first force, for example, a locking force. For example, the tang may be acted on by a second force, for example, a driving force. The tang is supported at two points from stress incident to such a force being applied to the tang.

A motorized window treatment, such as a motorized roller tube system or shade, may comprise a roller tube and a flexible member or material, such as a window shade fabric, attached to the roller tube. Driving of the roller tube may cause the roller tube to windingly receive or release the flexible material. A motorized window treatment may further include a drive assembly that may drive the roller tube (e.g., rotate the roller tube such that the flexible material winds and unwinds onto and from the roller tube).

As the flexible member is wound onto the roller tube, the material of the flexible member may be formed into layers (or "windings"). A portion of the flexible member may wound onto the roller tube and another portion of the flexible member may hang from the roller tube (e.g., a pendant portion). When the pendant portion of the flexible member completely covers a window, the window treatment (e.g., shade) is said to be closed. When the pendant portion of the flexible member is at a maximum winding (e.g., completely wound onto the roller tube), the window treatment (e.g., shade) is said to be open. As can be appreciated, a plurality of positions between open and closed exist, each position having an associated pendant portion of the flexible member, with an associated weight that creates an associated load due to gravity.

<FIG> illustrates a perspective view of an example motorized window treatment, such as a motorized roller shade <NUM>. The motorized roller shade <NUM> may include a covering material <NUM> (e.g., a flexible material, such as a shade fabric) windingly received around a roller tube <NUM>. The roller tube <NUM> may extend from a first end 3a to a second end 3b. A longitudinal axis <NUM> may extend from the first end 3a to the second end 3b of the roller tube <NUM>. The roller tube <NUM> may be rotatably supported by mounting brackets <NUM>, which may be attached to structure adjacent a window (e.g., a wall or ceiling) that may be covered by the covering material <NUM>. The roller tube <NUM> may be constructed of any appropriate material, such as, for example, aluminum, stainless steel, or plastic.

A hembar <NUM> may be connected to a lower edge of the covering material <NUM> and be oriented parallel to the lower edge of the covering material. The hembar <NUM> may be configured to weigh down the covering material <NUM>. Rotation of the roller tube <NUM> about the longitudinal axis <NUM> may cause the covering material <NUM> to be wound or unwound from the roller tube to raise and lower the hembar <NUM>.

The motorized roller shade <NUM> may comprise a motor drive unit <NUM> and an idler <NUM> that may each be configured to be connected to one of the respective mounting brackets <NUM>. The motor drive unit <NUM> may be located inside of, or otherwise coupled to, the first end 3a of the roller tube <NUM> and the idler <NUM> may be coupled to the second end 3b of the roller tube. The motor drive unit <NUM> may include a motor (not shown)configured to rotate the roller tube <NUM> to adjust the covering material <NUM> between a fully-closed position and a fully-open position and may be configured to retain the covering material <NUM> at any position intermediate to the fully-closed position and the fully-open position. The idler <NUM> may be coupled to the roller tube <NUM> (e.g., at the second end 3b) to allow for rotation of the roller tube relative to the mounting brackets <NUM> as the motor drive unit <NUM> rotates the roller tube. The motor of the motor drive unit <NUM> may be any appropriate drive member, such as, for example, a DC motor, an AC motor, or a stepper motor. The motorized roller shade <NUM> may include one or more batteries (not shown) configured to power the motor drive unit <NUM>. Alternatively, or additionally, the motor drive unit <NUM> may be configured to connect to an electrical system of a building in which the motorized roller shade <NUM> is installed. For example, the roller shade <NUM> may include an electrical cable configured to be connected to the electrical system. The motor drive unit <NUM> may further include a wireless communication circuit, such as a radio-frequency (RF) receiver or transceiver, for receiving wireless signals (e.g., RF signals). The motor drive unit <NUM> may be configured to raise and lower the hembar <NUM> to control the amount of daylight entering a space in response to a command received via the wireless signals.

Tuming to <FIG>, a drive assembly <NUM> (also referred to herein as a motor drive unit) is shown, which may be disposed within a roller tube (not depicted for simplicity of illustration, but which may be similar to the roller tube <NUM> of <FIG>) for rotating the roller tube between various positions. The drive assembly <NUM> may include a housing <NUM> (also referred to herein as a motor drive unit housing). As illustrated, a portion (e.g., here a top portion) of the housing <NUM> has been removed. The drive assembly <NUM> may include a drive motor <NUM> and a gear assembly <NUM>. The housing <NUM> may retain the drive motor <NUM> and the gear assembly <NUM>. The drive assembly <NUM>, and thus the drive motor <NUM>, may be configured to receive power from a direct-current (DC) supply and/or an alternating-current (AC) supply. Power may be supplied by wire (e.g., connected to a power supply/source that is external to the motorized window treatment) or by a power supply/source that is integral with the motorized window treatment. For example, the integral power supply may be one or more batteries that may be disposed within the roller tube. As another or additional example, the power supply/source may be a photovoltaic power source, such as a solar cell.

The drive assembly <NUM> may further include an electronic drive unit <NUM> configured to control the operation of the drive motor <NUM>. For example, the electronic drive unit <NUM> may receive commands (for example, ultimately from a user wishing to change a position of the flexible material), via a remote control unit or other external system controller, which result in operation of the drive motor <NUM>. For example, a command may be received by the electronic drive unit <NUM> that causes the electronic drive unit to control the operation of the drive motor <NUM> to cause movement in a rotational direction that results in opening of the motorized window treatment. For example, a command may be received by the electronic drive unit <NUM> that causes the electronic drive unit to control the operation of the drive motor <NUM> to cause movement in a rotational direction that results in closing of the motorized window treatment. A printed circuit board <NUM> may be provided for mounting control circuitry (not depicted) of the electronic drive unit <NUM>. The drive assembly <NUM> may further include a bearing sleeve <NUM> and bearing mandrels <NUM> that are disposed at a first end of the housing <NUM> of the drive assembly <NUM> for engaging an interior surface of a first end of the roller tube (not depicted) and that allow the roller tube to rotate relative to the housing <NUM> of the drive assembly. The drive assembly <NUM> may further include a mechanism <NUM> to interface or connect the housing <NUM> of the drive assembly to a mounting bracket (not depicted). According to one example, the housing <NUM> may be fixed/not rotate relative to the mounting bracket.

The drive assembly <NUM> may further include a drive puck <NUM> disposed at a second end of the housing <NUM>. The drive puck <NUM> may include features (such as longitudinal grooves) to promote engagement between an outer surface of the drive puck <NUM> and an inner surface of a second end of the roller tube (not depicted) when the drive assembly <NUM> is received within the roller tube. The drive puck <NUM> may be fixably connected to a puck shaft <NUM> that is rotatably supported with respect to the housing <NUM> by a drive bearing <NUM>. The puck shaft <NUM> may be operably connected to the gear assembly <NUM> such that actuation of the drive motor <NUM> rotates the gear assembly and thus the push shaft and thereby the drive puck <NUM>. Drive puck <NUM> in turn rotates the roller tube, thus winding and unwinding, for example, the flexible member onto and off of the roller tube.

The drive assembly <NUM> may further include a brake assembly <NUM> that may be disposed in the housing <NUM> and that receives the puck shaft <NUM>. Although a motorized window treatment may be balanced, for example, with counter springs to reduce the force required to wind the flexible member, as can be appreciated, it is not always possible to perfectly balance the flexible member's weight at all positions of the motorized window treatment. Accordingly, even spring-balanced motorized window treatments may require a brake assembly to hold the flexible member in a selected position. As will be discussed, the brake assembly <NUM> is engaged when the motor is not in use. When the motor is rotating a roller tube, for example, to a relatively more closed position of the shade or a relatively more open position of the shade, the brake assembly <NUM> is not engaged.

The brake assembly <NUM> may include a brake input <NUM>, a brake output <NUM>, a brake spring <NUM>, and a brake mandrel <NUM> (also referred to herein as a mandrel). A portion of the mandrel <NUM> projects toward the drive puck <NUM> and is surrounded by the brake input <NUM>, the brake output <NUM>, and the brake spring <NUM>. The mandrel <NUM> may be retained by the housing <NUM> and not rotate relative to the housing and may therefore also be referred to herein as the non-rotating mandrel. A gear cover <NUM> of the gear assembly <NUM> may be disposed adjacent to the brake mandrel <NUM>. A motor adapter <NUM> may be disposed between the motor <NUM> and the gear cover <NUM> and may connect the output of the motor to the gear assembly <NUM>. In operation, the puck shaft <NUM> may pass through the brake assembly <NUM>, which may be adapted to engage the puck shaft to prevent relative rotation between the motor <NUM> and the drive puck <NUM> when the flexible member is not being wound/unwound (e.g., when the shade is not in use). It is understood that a load (e.g., a gravitational load) is applied to the roller tube due to a weight of an unwound portion of the flexible member (not depicted) and an optional hembar (if present). Engagement of the brake assembly <NUM> counteracts the load and prevents the flexible member from unwinding (e.g., when the shade is not in use).

Referring now to <FIG>, a brake spring <NUM> may be formed from wire (such as a single piece of wire) and may comprise a plurality of (e.g., two or more) wraps or coils 38a. Both a diameter of the wire and a number of wraps may have an effect on a brake drag force. The brake spring <NUM> may terminate at each respective end in a bend 38b, thereby creating a tang 38c having a distal end 38d. The brake spring <NUM> may be disposed on the non-rotating mandrel <NUM>. The brake spring <NUM> may have an intemal or inner diameter 38e defined by the innermost surface of the plurality of wraps 38a. When the spring is in a relaxed state, diameter 38e may be slightly smaller than the non-rotating mandrel <NUM> (<FIG>). The brake input <NUM> and the brake output <NUM> are each rotatable and adapted to engage at least one of the tangs 38c of the brake spring <NUM>. When the brake input <NUM> is rotated in either direction, the brake input pushes on one or more of the tangs 38c, thereby relaxing the brake spring <NUM> (e.g., increasing the internal diameter defined by the plurality of wraps 38a). The brake spring <NUM> then slides on the non-rotating mandrel, allowing the brake output <NUM> to be driven by the brake input <NUM>.

In the absence of rotation of the brake input <NUM>, gravity may cause a load/force on the flexible member, which if unchecked, could result in unwinding and subsequent lowering of the position of the flexible member. In response, this load may cause the brake output <NUM> to push one or more of the tangs 38c, thereby "back driving" the brake spring <NUM>. Back driving the brake spring <NUM> may cause a decrease in the internal diameter 38e defined by the plurality of wraps 38a, and the brake spring <NUM> may grip tightly onto the non-rotating mandrel <NUM>, preventing rotation of the brake output <NUM> and thus puck shaft <NUM>. As a result, the flexible member may be held in position by the brake assembly <NUM>.

One problem with brake spring <NUM> is that the tangs 38c may, for example, bend such as at bend 38b. Each of the tangs 38c is essentially a cantilever, taking all the force when the brake spring <NUM> is back driven which may, for example, cause the tangs 38c to bend and thus cause the brake assembly to slip and the flexible member to undesirably move beyond the desired position. To compensate and prevent the tangs 38c from bending, heavier spring wire may be used to form the brake spring <NUM>. However, heavier wire may cause the brake spring <NUM> to have significant drag (e.g., against the non-rotating mandrel) when the brake output is driven by the brake input <NUM> because it is more difficult for the brake input to relax the brake spring <NUM> (e.g., increasing the internal diameter 38e defined by the plurality of wraps 38a) and thereby for the brake spring <NUM> to slide on the non-rotating mandrel. This drag can cause energy efficiency problems, as one example. For example, in the case of battery-powered shades, when a brake spring like that of <FIG> is used, the operating friction between the brake spring <NUM> and non-rotating mandrel <NUM> can consume as much of the battery energy as moving the shade.

Accordingly, what is needed are improved brake assemblies for motorized window treatments employing, for example, motorized roller tube systems, including battery-powered shades, improved brake springs for the same, and methods of reducing brake drag force in brake assemblies of motorized window treatments.

<FIG> depicts a brake spring <NUM> according to the invention. The brake spring <NUM> comprises wire formed into a plurality of coils 46a. The number of coils and the diameter of the wire may be determined based desired drag for a shade application (such, for example, using Equations <NUM> and <NUM> described herein to determine the desired performance). The plurality of coils 46a terminate at a first bend 46b, a tang 46c, a second bend 46d, a support portion 46e, and a tip 46f (46b-46f being collectively referred to as a tang assembly). A variety of shapes for tang assemblies are contemplated, for example, the tang assemblies of <FIG> and <FIG> is described as generally L-shaped.

The first bend 46b is configured such that the tang 46c extends radially from the plurality of coils 46a, which allows interaction with an input member or output member as will be described with respect to <FIG>. The brake spring <NUM> has an internal or inner diameter <NUM>. The internal or inner diameter <NUM> varies, depending on whether the brake spring <NUM> is in a relaxed state or a back-driven state.

As depicted, the tang assemblies 46b-46f are mirror images of each other and have substantially the same geometries. The relative circumferential position of the tang assemblies is dictated by the length of the wire (e.g., number of wraps) forming the brake spring <NUM>. The second bend 46d, the support portion 46e, and the tip 46f are disposed after the tang 46c. The support portion 46e supports the tang 46c when the tang is acted on by a force. The support portion 46e may engage an input member (such as will be described as input member <NUM> or input member <NUM>). The support portion 46e greatly reduces the hazard of the tang 46c bending (or even breaking), e.g., at first bend 46b, because the stress is shared between the first bend and the support portion. Having the tang 46c supported by the support portion 46e allows for the use of a smaller wire diameter for the brake spring <NUM>, which creates less drag when rotating about the mandrel in a driven state.

<FIG> and <FIG> depict a brake assembly <NUM> that is adapted to be used in motorized window treatments, such as are associated with motorized roller tube systems. As one example, brake assembly <NUM> may be used within a drive assembly, such as in place of brake assembly <NUM> of drive assembly <NUM> of <FIG>. For description purposes only, drive assembly <NUM> (<FIG>) may be used in describing operation of the brake assembly <NUM>. Engagement of the brake assembly <NUM> may counteract the gravitational load/force associated with the pendant portion of a flexible member and prevents the flexible member from unwinding when the window treatment is at rest (e.g., the motor is not being actuated).

The brake assembly <NUM> comprises a mandrel <NUM>. The brake mandrel <NUM> may include a base <NUM>, which may include features to aid attachment within a drive assembly, such as within a housing <NUM> of drive assembly <NUM> (<FIG>). Base <NUM> of brake assembly <NUM> may be fixably attached to housing <NUM> of drive assembly <NUM> such that the brake mandrel <NUM> does not rotate relative to the housing. In this fashion, the brake mandrel <NUM> may also be referred to herein as a non-rotating mandrel. A body <NUM> may extend from the base <NUM>. The body <NUM> may be annular in shape. The body <NUM> may have a distal portion <NUM>.

The distal portion <NUM> may also be one or more of annular in shape and coaxial with the body <NUM>. The distal portion <NUM> may comprise an outer surface 58a for receiving a brake spring <NUM> (the brake spring <NUM> may be substantially similar to the brake spring <NUM> of <FIG>). The distal portion <NUM> may also define a bore 58b which extends all the way through the brake mandrel <NUM>. A plurality of ribs 58c (three are shown in <FIG>, although there may be fewer or more than three) may be disposed within the bore 58b. The ribs 58c may extend parallel to an axis defined by the bore 58b and may extend, for example, for at least a length equally the length of the distal portion <NUM>. As another example, the plurality of ribs 58c may extend the entire length of the bore 58b (e.g., a length of the bore represented by a length of the brake mandrel <NUM>). A drive shaft (not depicted in <FIG> and <FIG>) pass through the bore 58b, but may not contact the plurality of ribs 58c, thereby allowing the drive shaft to spin freely within the brake mandrel.

The brake spring <NUM> may include a plurality of wraps or coils 60a. The brake spring may be disposed about the mandrel <NUM>, positioned on the surface 58a of the body <NUM> of the mandrel. The brake spring <NUM> may have an intemal or inner diameter <NUM> defined by the innermost surface of the plurality of coils 60a. When in a relaxed state, diameter <NUM> may be slightly smaller than diameter 58d of the distal portion <NUM> of body <NUM> (e.g., diameter 58d may extend to surface 58a). In a first rotational state, as will be described, the brake spring <NUM> may be tensioned (e.g., back driven) and may tightly engage the surface 58a of distal portion <NUM>, preventing relative rotation between the brake spring <NUM> and the brake mandrel <NUM>. In tum, this prevents the drive shaft, and thus the roller tube, from spinning, and thereby, the flexible member from unwinding, such as due to gravity, from the roller tube. Accordingly, the first rotational state of the brake spring <NUM> may be a nonrotational state with respect to the surface 58a of the mandrel <NUM>.

In a second rotational state, as will be described, the brake spring <NUM> may be forcibly relaxed (e.g., driven open, thereby increasing inner diameter <NUM> of the brake spring), allowing relative rotation between the brake spring <NUM> and the mandrel <NUM>, albeit with some associated drag, since diameter <NUM> may (e.g., may still) be slightly smaller than diameter 58d of the distal portion <NUM> of body <NUM>. In this second rotational state, the motor <NUM> of the drive assembly <NUM> may drive/rotate puck shaft <NUM> and thus puck assembly <NUM> and the roller tube, thereby driving the flexible member to a new position, such that the window treatment is further opened or further closed. Accordingly, the second rotational state of the brake spring <NUM> may involve clockwise or counterclockwise rotation of the brake spring with respect to the surface 58a of the mandrel <NUM>, and may be referred to as a driven state.

The brake spring <NUM> may comprise wire formed into the plurality of coils 60a. A diameter (e.g., thickness) of the wire and a number of coils (e.g., wraps) may be determined based on a desired application, for example, using Equation <NUM> (drag to lower the shade, e.g., at a constant speed) and Equation <NUM> (drag to lift the shade): <MAT> <MAT> wherein:.

For example, viewing <FIG>, the Mandrel Outer Diameter (OD) may be a diameter between the two furthest separated points of the surface 58a (e.g., diameter 58d). For example, the Spring Inner Diameter may refer to diameter <NUM> defined between the innermost surfaces of the plurality of coils 60a. The coefficient of friction may be between the mandrel material and the wire material.

The plurality of coils 60a may end in a radial first bend 60b. As depicted, the first bend 60a may be a perpendicular or <NUM> degree bend, but as will be appreciated, the first bend may be a gradual curve or a series of curves. A tang 60c may extend from the first bend 60b. A second bend 60d may be disposed at an end of the tang 60c, e.g., after the tang. The second bend 60d may be opposite the first bend 60b. As depicted, the second bend 60d may be a perpendicular or <NUM> degree bend, but as will be appreciated, the second bend may be a gradual curve or a series of curves. A support portion 60e may be disposed after the second bend 60d, the support portion terminating in a tip 60f (see <FIG>) which is the distal end of the brake spring <NUM>.

The support portion 60e may support the tang 60c when the tang is acted on by a force. The force may act on a portion of the tang 60c or substantially all of the tang. Examples of forces acting upon the tang 60c may include a first force applied to back drive the plurality of coils 60a, thereby causing diameter <NUM> of the spring to contract and the coils to engage the surface 58a of the mandrel <NUM>, and a second force applied to relax the plurality of coils, thereby causing diameter <NUM> of the spring to expand and the coils to slip with respect to the surface 58a of the mandrel.

As discussed with reference to brake spring <NUM> of <FIG>, tangs (e.g., tangs 38c) acted as cantilevers and were susceptible to bending, for example, at the bend (e.g., bend 38b) which formed the tang. A bent tang may result in a flexible member slowly unwinding to a fully closed position, for example, after being set to a position, which may annoy consumers. The support portion 60e greatly reduces the forces on tang 60c and thus preventing tang 60c from bending, e.g., at first bend 60b, because the stress is shared between the first bend and the support portion 60e. In addition, having the tang 60c supported by the support portion 60e may allow for the use of a smaller wire diameter for the brake spring <NUM>, which may create less drag when the spring <NUM> is rotating about the mandrel in the driven state. Less drag requires less effort from a motor, which may improve battery life, which is one consideration/advantage for battery-powered shades.

The first bend 60b, the tang 60c, the second bend 60d, the support portion 60e, and the tip 60f may be collectively referred to as a tang assembly. Although only one tang assembly is visible in <FIG> and <FIG>, it is understood that there may be a substantially similar arrangement on the other end of the plurality of coils 60a (see, e.g., <FIG>). In some embodiments, the tang assemblies may be mirror images of each other (e.g., the other one points in the opposite direction, for example, if one tang assembly is pointing clockwise when viewed on end (e.g., along an axis defined by the mandrel distal portion <NUM>), the other tang assembly is pointing counterclockwise). In some embodiments, the geometry of each of the tang assemblies is different. In any case, the relative circumferential position of the tang assemblies is dictated by the length of the wire (e.g., number of wraps) forming the brake spring <NUM>.

The brake assembly <NUM> may further comprise an input member <NUM>. The input member <NUM> may comprise an annular base <NUM> defining a bore 64a. A coupler <NUM> may be disposed in the bore 64a. The coupler <NUM> may define a bore 66a that is adapted to engage a drive shaft (not depicted in <FIG> and <FIG>) to rotate the input member <NUM> around an axis that is coaxial with the bore 66a. In a first direction of rotation of the drive shaft and thus input member <NUM>, movement is imparted to a puck (for example, such as the drive puck <NUM> of <FIG>) which engages the roller tube such that the flexible member is wound about the roller tube and the flexible member is raised. In an opposite direction of rotation of the drive shaft and thus input member <NUM>, the flexible member is unwound from the roller tube and the drive shaft and thus is lowered. For clarity, in both directions of rotation of the input member <NUM>, the brake spring <NUM> is in the driven state, as will be described. The bore 66a may have features (e.g., splines) to engage the drive shaft, although other mechanisms may be used.

A body <NUM> may extend from the base <NUM> of the input member <NUM> in the direction of the brake spring <NUM> and the mandrel <NUM>. The body <NUM> may be annular in shape. The body <NUM> may have a first surface 68a. An engagement surface 68b may be disposed on the body <NUM> for engaging a portion of an output member <NUM>, the engagement surface being perpendicular to the surface 68a. A sidewall 68c may extend from the body <NUM> in the direction of the brake spring <NUM> and the mandrel <NUM>. A recessed surface 68d may be adjacent to the sidewall 68c and be recessed or stepped down relative to the sidewall 68c. The recessed surface 68d may receive a portion of the brake spring <NUM>, such as the support portion 60e and the tip 60f. The recessed surface 68d may support the support portion 60e and the tip 60f of the brake spring <NUM>, thereby reducing the stress on the first bend 60b imparted by a force acting on the tang 60c.

An edge 68e of the body <NUM> may be adjacent to the recessed surface 68d for engaging a portion of the brake spring <NUM>, such as the tang 60c, when the brake assembly <NUM> is in the second rotational state. The input member <NUM> may be symmetrical, for example, it may have similar features disposed on the other side of the brake assembly <NUM> for engaging the other tang assembly.

As an example, when the motor of the motorized window treatment is actuated to raise or lower the flexible member, the drive shaft may rotate the input member <NUM>. Rotation of the input member <NUM> may cause edge 68e to apply a force to the tang 60c, driving the brake spring <NUM>, causing the brake spring to enlarge and disengage from (or at least slip with respect to) the surface 58a of the mandrel <NUM> (e.g., diameter <NUM> becoming larger), and allowing the drive shaft (and thus the puck, and thereby roller tube and flexible material) to freely rotate relative to the mandrel. Stress experienced by the first bend 60b of the brake spring <NUM> due to the force applied to the tang 60c may be partially offset by the support portion 60e engaging the recessed surface 68d of the input member <NUM>.

The brake assembly <NUM> further comprises an output member <NUM>. In some embodiments, unlike the spring <NUM> and input member <NUM>, the output member <NUM> may not be symmetrical. However, it may be beneficial to have a symmetrical output member <NUM>, for example, for universal compatibility with right-handed or left-handed configurations of window treatments.

The output member <NUM> comprises an annular base <NUM> defining a bore 72a. The bore 72a is adapted to receive a puck shaft (not depicted in <FIG>&<NUM>) which is coupled to a puck (for example, such as the drive puck <NUM> of <FIG>) which engages the roller tube. A plurality of ribs <NUM> may extend radially from the base <NUM>. Several of the plurality of ribs <NUM> also extend axially in the direction of the input member <NUM>, the brake spring <NUM>, and the mandrel <NUM>. The plurality of ribs <NUM> need not be identical; for example, the plurality of ribs may not all be the same length. An engagement surface 74a may be disposed on one of the plurality of ribs <NUM> for engaging the tang 60c of the brake spring <NUM> when the brake assembly <NUM> is in the first rotational state. For example, the input and output members may engage opposing sides of the tang 60c.

For example, when the motor of the motorized window treatment is not actuated, a gravitational load is applied to the roller tube due to a weight of an unwound (e.g., pendant) portion of the flexible member. This load is transferred to the puck, and thence to the output member <NUM> via the puck shaft. Rotation of the output member <NUM> causes the engagement surface 74a to apply a force to the tang 60c, back driving the brake spring <NUM>, causing the brake spring to engage the surface 58a of the mandrel <NUM> (e.g., diameter <NUM> to become smaller), stopping the rotation of the brake spring, the output member, and the puck, and thereby preventing the flexible member from unwinding. Stress experienced by the first bend 60b of the brake spring <NUM> due to the force applied to the tang 60c is partially offset by the support portion 60e engaging the recessed surface 68d of the input member <NUM>.

A body <NUM> extends from the base <NUM> of the output member <NUM> in the direction of the input member <NUM>, the brake spring <NUM>, and the mandrel <NUM>. One or more of the plurality of ribs <NUM> are also attached to the body <NUM>. A sidewall 76a extends axially from the body <NUM> in the direction of the input member <NUM>, the brake spring <NUM>, and the mandrel <NUM>. The sidewall 76a may be disposed between a portion of the plurality of ribs <NUM>. An engagement surface 76b may be disposed on the body <NUM>, for example, on a side of a rib distal to sidewall 76a, for engaging the engagement surface 68b of the input member <NUM>. When driven by the motor in a first rotational direction, the input member <NUM> rotates (clockwise as illustrated), causing engagement surface 68b to contact engagement surface 76b and the output member <NUM> to thus rotate, with the puck shaft imparting the output member's rotation to the puck, thereby winding or unwinding the flexible member depending on the rotational direction of the motor.

As seen in <FIG>, the sidewall 68c and the recessed surface 68d of the input member <NUM> cover a portion of the plurality of coils 60a, a portion of the body <NUM> of the mandrel <NUM>, and the distal portion <NUM>. The support portion 60e and the tip 60f of the brake spring <NUM> engage the recessed surface 68d. The sidewall 76a of the output member <NUM> covers another portion of the plurality of coils 60a, a portion of the body <NUM> and the distal portion <NUM> of the mandrel <NUM>, and the base <NUM> and the surface 68a of the input member <NUM>. Due to the sidewall 68c and the recessed surface 68d of the input member <NUM> and the sidewall 76a of the output member <NUM> covering most of the plurality of coils 60a, only a portion of the tang 60c, the second bend 60d, the support portion 60e, and the tip 60f of the brake spring <NUM> are visible in <FIG>.

In operation, as will be discussed, the brake assembly <NUM> is engaged when a motor is not in use. When the motor is rotating a roller tube, for example, to a relatively more closed position of the window treatment or a relatively more open position of the window treatment, the brake assembly <NUM> is not engaged. Although some drag is associated with the brake assembly <NUM>, it is less than a conventional amount, such as may be experienced with a spring of <FIG>, for example (for example, because of the smaller diameter wire that springs with the described support portions may employ), and thus requires less energy to overcome. The brake assembly <NUM> may be particularly useful for battery-powered window treatments, such as battery-powered shades, including spring-balanced motorized window treatments (e.g., spring-balanced battery-powered shades). The brake assembly <NUM> may be associated with increased battery life for battery-powered window treatments.

In the first rotational state, the brake spring <NUM> is tensioned by the action of gravity acting on the flexible member, the engagement surface 74a of the output member <NUM> applying a force to the tang 60c, back driving the brake spring and causing the brake spring to engage the surface 58a of the mandrel <NUM>, stopping the rotation of the brake spring, the output member, and the puck, and thereby preventing the flexible member from unwinding. In the second rotational state, a motor acts on the drive shaft (e.g., clockwise or counterclockwise), rotating the input member <NUM>, causing the edge 68e to exert a force on the tang 60c of the brake spring <NUM>, thereby relaxing the brake spring and allowing rotation of the brake spring, the output member <NUM> (through engagement surface 68b contacting engagement surface 76b), and the puck. Accordingly, the motor may drive the flexible member to a new position, such that the window treatment (e.g., flexible material) further opens or further closes.

<FIG> depict a brake assembly <NUM> in the first rotational state, which may be referred to also as a locked state. The brake assembly <NUM> may be an example of the brake assembly <NUM> depicted in <FIG> and <FIG>. The brake assembly <NUM> may be installed in either end of a roller tube. For example, right-handed or left-handed configurations of window treatments exist (with reference to the disposition of the brake assembly <NUM> in the roller tube). A symmetrical design will be beneficial, as if installed on a right end of a roller tube, for example, a different tang assembly will act as a lock than if the brake assembly is installed on a left end of a roller tube, when the other tang assembly would act as the lock.

The brake assembly <NUM> comprises a mandrel <NUM>. The mandrel <NUM> includes a base <NUM> and a body <NUM> extending from the base <NUM>. The body <NUM> may have a distal portion <NUM> which comprises an outer surface 88a for receiving a brake spring <NUM>. The distal portion <NUM> defines a bore 88b. A plurality of ribs 88c may be disposed within the bore 88b (three ribs are shown in <FIG>) and extend parallel to an axis defined by the bore.

A brake spring <NUM> is positioned on the surface 88a of the distal portion <NUM> of the mandrel <NUM>. In the first rotational state (depicted), the brake spring <NUM> is tensioned and tightly engages the surface 88a, preventing relative rotation between the brake spring <NUM> and the mandrel <NUM>. The brake spring <NUM> may comprise wire formed into a plurality of coils 90a. The number of coils and the diameter of the wire may be determined based on the window treatment application (such, for example, using Equations <NUM> and <NUM> described herein to determine the desired performance). The plurality of coils 90a may terminate at a pair of tang assemblies, a first tang assembly comprising a first bend 90b, a tang 90c, a second bend 90d, a support portion 90e, and a tip 90f and a second tang assembly comprising a first bend <NUM>'b, a tang <NUM>'c, a second bend <NUM>'d, a support portion <NUM>'e, and a tip <NUM>'f. As depicted, the tang assemblies are mirror images of each other and have substantially the same geometries. The relative circumferential position of the tang assemblies is dictated by the length of the wire (e.g., number of wraps) forming the brake spring <NUM>. Any description relating to 90b-9f may also apply to <NUM>'a-<NUM>'f, but only the former are discussed in the following for ease of explanation.

It is noted that the second bend 90d, the support portion 90e, and the tip 90f are disposed after the tang 90c. The support portion 90e supports the tang 90c when the tang is acted on by a force. The support portion 90e greatly reduces the tang 90c from bending, e.g., at first bend 90b, because the stress is shared between the first bend and the support portion. According to a further example, having the tang 90c supported by the support portion 90e may allow for the use of a smaller wire diameter for the brake spring <NUM>, which creates less drag when rotating about the mandrel in a driven state. Less drag requires less effort from a motor, which improves battery life, a very important consideration for battery-powered window treatments.

The brake assembly <NUM> further comprises an input member <NUM>. The input member <NUM> defines a bore (not visible) which retains a coupler <NUM> defining a bore 96a that is adapted to engage a drive shaft (not depicted). The drive shaft is adapted to be driven by the motor to rotate the input member <NUM>; however, in the depicted first rotational state, the motor is not actuated. The input member <NUM> comprises a body <NUM> having a sidewall 98c. A recessed surface 98d is adjacent to and stepped down from the sidewall 98c for receiving the support portion 90e and the tip 90f of the brake spring <NUM>. An edge 98e of the body <NUM> is adjacent to the recessed surface 98d for engaging a portion of the brake spring <NUM>, such as the tang 90c, when the brake assembly <NUM> is in a second rotational state (<FIG>). As illustrated, the input member <NUM> is symmetrical, and thus has a recessed surface <NUM>'d and edge <NUM>'e, e.g., to accommodate the second tang assembly comprising the first bend <NUM>'b, the tang <NUM>'c, the second bend <NUM>'d, the support portion <NUM>'e, and the tip <NUM>'f.

The brake assembly <NUM> further comprises an output member <NUM>. The output member <NUM> comprises an annular base <NUM> defining a bore (not visible in <FIG>) which is adapted to receive a drive shaft (not depicted) which may be coupled to a puck (such as the drive puck <NUM>) which engages the roller tube (not depicted). A plurality of ribs <NUM> may extend radially from the base <NUM>. Several of the plurality of ribs <NUM> may also extend axially in the direction of the input member <NUM>, the brake spring <NUM>, and the mandrel <NUM>. An engagement surface 104a may be disposed on one of the plurality of ribs <NUM> for engaging the tang 90c of the brake spring <NUM> when the brake assembly <NUM> is in the first rotational state (<FIG>).

A body <NUM> extends from the base <NUM> in the direction of the input member <NUM>, the brake spring <NUM>, and the mandrel <NUM>. The plurality of ribs <NUM> are also attached to the body <NUM>. A sidewall 106a extends axially from the body <NUM> in the direction of the input member <NUM>, the brake spring <NUM>, and the mandrel <NUM>. The sidewall 106a may be disposed between a portion of the plurality of ribs <NUM>. An engagement surface 106b may be disposed on the body <NUM> for engaging an engagement surface 98b (<FIG>) of the body <NUM> of the input member <NUM>.

In operation, a gravitational load is applied to the roller tube due to a weight of an unwound (e.g., pendant) portion of the flexible member. This load is transferred to the puck, and thence to the output member <NUM> via a drive shaft, such as the puck shaft <NUM> (<FIG>). Rotation of the output member <NUM> causes the engagement surface 104a to apply a force to the tang 90c, back driving the brake spring <NUM>, causing the plurality of coils 90a to engage the surface 88a of the mandrel <NUM>, stopping rotation of the brake spring, the output member, and the puck, and thereby preventing the flexible member from unwinding. Stress experienced by the first bend 90b of the brake spring <NUM> due to the force applied to the tang 90c is partially offset by the support portion 90e engaging the recessed surface 98d of the input member <NUM>. The support portion 90e greatly reduces the forces of the tang 90c and thus preventing tang 90c from bending, e.g., at first bend 90b, because the stress is shared between the first bend and the support portion. The support portion 90e may slide along the recessed surface 98d.

<FIG> depict the brake assembly <NUM>, as previously described and using the same reference numerals, in the second rotational state, which may be referred to also as a driven state. The motor has driven the drive shaft to rotate the input member <NUM> (e.g., clockwise in <FIG>). This causes the edge 98e of the input member <NUM> to exert a force on the tang 90c of the brake spring <NUM>, thereby relaxing the brake spring (e.g., the inner diameter of the plurality of coils 90a increases in response to the force). The plurality of coils 90a slip with respect to the surface 88a of the mandrel <NUM>, and allowing rotation of the brake spring <NUM>, the output member <NUM>, and the puck (not depicted). Accordingly, the motor may drive the flexible member to a new position, such that the window treatment further opens or further closes. The recessed surface 98d supports the support portion 90e of the brake spring <NUM>, reducing stress placed on the first bend 90b by the force acting on the tang 90c.

<FIG> depicts a brake spring <NUM> according to another embodiment, which may be used in a brake assembly similar to those described herein. The brake spring <NUM> may comprise wire formed into a plurality of coils 110a. The number of coils and the diameter of the wire may be determined based on the window treatment application (such, for example, using Equations <NUM> and <NUM> described herein to determine the desired performance). The plurality of coils 110a may terminate at a pair of tang assemblies, each tang assembly comprising a first bend 110b, a tang 110c, and a second bend 110d. The second bend 110b is configured such that the tang 110c extends radially from the plurality of coils 110a. In this embodiment, the tang 110c may only interact with an output member. A support portion 110e and a tip 110f are disposed after the second bend 110d. The support portion 110e comprises two straight portions divided by a bend. The portion of the support portion 110e that is radial to the plurality of coils 110a (e.g., the portion parallel to the tang 110c) may engage, e.g., may only engage, an input member (such as at edge 98e of the input member <NUM> in <FIG>). The tip 110f may engage an input member having a feature similar to the recessed portion (such as at recessed portion 98e of the input member <NUM> in <FIG>) or, preferably, may engage a mandrel directly (such as surface 58a of the distal portion <NUM> of the mandrel <NUM> (<FIG>)). The brake spring <NUM> may have an internal or inner diameter <NUM> defined by the innermost surface of the plurality of coils 110a. When in a relaxed state, the diameter <NUM> may be slightly smaller than a diameter of a mandrel it engages (e.g., as surface 58a of the distal portion <NUM> of the mandrel <NUM> (<FIG>)).

As depicted, the tang assemblies are mirror images of each other and have substantially the same geometries. The relative circumferential position of the tang assemblies is dictated by the length of the wire (e.g., number of wraps) forming the brake spring <NUM>. The second bend 110d, the support portion 110e, and the tip 110f are disposed after the tang 110c. The support portion 110e and the tip 110f support the tang 110c when the tang is acted on by a first force, for example, a locking force applied by an output member (such as at <FIG>). The first bend 110b supports the support portion 110e when the support portion is acted on by a second force, for example, a driving force applied by an input member (such as at <FIG>). Stress incident to a force (e.g., to affect the plurality of coils 110a) acting on a radial member (e.g., the tang 110c or support portion 110e) to affect the plurality of coils 110a is reduced because the stress is shared between two points. For example, stress is shared between the first bend 110b and the tip 110f. Having two points of support allows for the use of a smaller wire diameter for the brake spring <NUM>, which creates less drag when rotating about the mandrel in a driven state. The tang assembly of <FIG> may be described as generally U-shaped.

<FIG> depicts a brake spring <NUM> according to another embodiment, which may be used in a brake assembly similar to those described herein. The brake spring <NUM> may comprise wire formed into a plurality of coils 120a. The number of coils and the diameter of the wire may be determined based on the window treatment application (such, for example, using Equations <NUM> and <NUM> described herein to determine the desired performance). The plurality of coils 120a may terminate at a pair of tang assemblies, each tang assembly comprising a first bend 120b, a tang 120c, and a second bend 120d. The second bend 120b is configured such that the tang 120c extends radially from the plurality of coils 120a. In this embodiment, the tang 120c may only interact with an output member. A support portion 120e and a tip 120f are disposed after the second bend 120d. The support portion 120e comprises three straight portions divided by a pair of bends. The portion of the support portion 120e that is radial to the plurality of coils 120a (e.g., parallel to tang 120c) may engage, e.g., may only engage, an input member (such as at edge 98e of the input member <NUM> in <FIG>). The portion of the support portion 120e that is adjacent to the plurality of coils 120a may engage an input member having a feature similar to the recessed portion (such as at recessed portion 98e of the input member <NUM> in <FIG>) or may engage a mandrel directly (such as surface 58a of the distal portion <NUM> of the mandrel <NUM> (<FIG>)). The tip 130f may engage an input member having a feature similar to the recessed portion. The brake spring <NUM> may have an internal or inner diameter <NUM> defined by the innermost surface of the plurality of coils 120a. When in a relaxed state, the diameter <NUM> may be slightly smaller than a diameter of a mandrel it engages (e.g., as surface 58a of the distal portion <NUM> of the mandrel <NUM> (<FIG>)).

As depicted, the tang assemblies are mirror images of each other and have substantially the same geometries. The relative circumferential position of the tang assemblies is dictated by the length of the wire (e.g., number of wraps) forming the brake spring <NUM>. The second bend 120d, the support portion 120e, and the tip 120f are disposed after the tang 120c. The support portion 120e supports the tang 120c when the tang is acted on by a first force, for example, a locking force. The first bend 120b supports the support portion 120e when the radial portion of the support portion is acted on by a second force, for example, a driving force. Stress incident to a force (e.g., to affect the plurality of coils 120a) acting on a radial member (e.g., the tang 120c or support portion 120e) is reduced because the stress is shared between two points. For example, stress is shared between the first bend 120b and the portion of the support portion 120e that is adjacent to the plurality of coils 120a. Having two points of support allows for the use of a smaller wire diameter for the brake spring <NUM>, which creates less drag when rotating about the mandrel in a driven state. The tang assembly of <FIG> may be described as generally Ω-shaped.

<FIG> depicts a plan view of a brake spring <NUM> according to another embodiment, which may be used in a brake assembly similar to those described herein. The brake spring <NUM> may comprise wire formed into a plurality of coils 130a. The number of coils and the diameter of the wire may be determined based on the window treatment application (such, for example, using Equations <NUM> and <NUM> described herein to determine the desired performance). The plurality of coils 130a may terminate at a pair of tang assemblies, each tang assembly comprising a first bend 130b, a tang portion 130c, and a second bend 130d. In this embodiment, the tang portion 130c may be shaped as a loop. The tang portion 130c may engage an output member on a first side and an input member on a second (e.g., opposing) side. A support portion 130e and a tip 130f are disposed after the second bend 130d. The support portion 130e may engage a mandrel (e.g., the same surface of a mandrel that may be engaged by the plurality of coils). The brake spring <NUM> may have an internal or inner diameter <NUM> defined by the innermost surface of the plurality of coils 130a. When in a relaxed state, the diameter <NUM> may be slightly smaller than a diameter of a mandrel it engages (e.g., as surface 58a of the distal portion <NUM> of the mandrel <NUM> (<FIG>)).

As depicted, the tang assemblies are mirror images of each other and have substantially the same geometries. The relative circumferential position of the tang assemblies is dictated by the length of the wire (e.g., number of wraps) forming the brake spring <NUM>. The second bend 130d, the support portion 130e, and the tip 130f are disposed after the tang 130c. The support portion 130e supports the tang 130c when the tang is acted on by a first force, for example, a locking force, or by a second force, for example, a driving force. Stress incident to a force (e.g., to affect the plurality of coils 130a) acting on the tang 130c is reduced because the stress is shared between two points. For example, stress is shared between the first bend 130b and the support portion 130e. Having two points of support allows for the use of a smaller wire diameter for the brake spring <NUM>, which creates less drag when rotating about the mandrel in a driven state. The tang assembly of <FIG> may be described as generally O-shaped.

Claim 1:
A window treatment comprising:
a motorized roller tube system; and
brake assembly comprising:
a mandrel (<NUM>, <NUM>, <NUM>); and
a brake spring (<NUM>, <NUM>, <NUM>) disposed upon the mandrel, the brake spring comprising a plurality of coils (46a, 110a, 120a) and a tang (46c, 110c, 120c) extending from the plurality of coils, the tang having a first bend (46b, 110b, 120b) at a first end of the tang adjacent the plurality of coils, wherein the first bend bends the tang in a first direction to extend in a radial direction of the coil spring, and a second bend (46d, 110d, 120d) at a second end of the tang, wherein the second bend forms the tang in a L-shape in a second direction opposite to the first direction, wherein a support portion (46e, 110e, 120e) coplanar with the spring coils extends from the second bend (46d, 110d, 120d).