Abstract: A cord-winding device for a Venetian blind includes: a first reel; a driving unit including a driving wheel and a spring-winding wheel; and a brake unit including a driven gear, a driving member, a ratchet wheel sleeved on the driving member, a plurality of friction members disposed between the driving member and the ratchet wheel, and at least pawl biased to engage the ratchet wheel. When the driven gear is driven by the first reel to rotate in a direction, rotation of the ratchet wheel is stopped by the pawl so that the driving member drives the friction members to rotate, and when the driven gear is driven by the driving wheel to rotate in an opposite direction, the driving member drives rotation of the friction members and, thus, the ratchet wheel.

Abstract: A window covering comprises an upper rail, a window shade located below the upper rail, a lower rail located below the window shade, a first clamping assembly and a second clamping assembly located at two sides of the lower rail and spaced from each other, and a cord winding assembly located in the lower rail to connect to the first clamping assembly and the second clamping assembly. A first cord and a second cord run through two opposite sides of the window shade to fasten to the cord winding assembly. The lower rail can be moved upwards or downwards by a user to retract or expand the window shade through the first and second cord. Besides, the distal ends of the first and second cords can be hidden in the cord winding assembly in the lower rail, thus can prevent the cords from entangling children to avoid accidents.

Abstract: A window covering comprises an upper rail, a window shade, a lower rail, a press member located in the lower rail and extended therefrom, a first press assembly and a second press assembly located in the lower rail and spaced from each other to contact the press member, and a cord winding assembly located in the lower rail to connect to the first and second press assemblies. A first cord and a second cord run through the window shade to fasten to the cord winding assembly. A user can depress the press member and push or pull the lower rail upwards or downwards, so that the window shade can be retracted upwards or extended downwards through the first and second cords. Moreover, the first and second cords are held inside the lower rail, hence accident caused by the exposed cords can be prevented.

Abstract: A cord-winding assembly of a window blind includes a first spool and a second spool. The first spool has a first axis extending in an axial direction. A plurality of first grooves is formed on an outer periphery of the first spool. The first grooves are parallel to each other. Each of the plurality of first grooves has a circumferential length different from other first grooves. The second spool has a second axis extending in the axial direction. The first and second axes are parallel to each other. A plurality of second grooves is formed on an outer periphery of the second spool. The second grooves are parallel to each other.

Abstract: A motorizable tilt shade system includes a header system where the header system includes an integral header attachment connection. At least one cord spool is provided within the header system and is connected with at least one suspension cord. A shade is suspended from the at least one suspension cord and a tilt cord pulley is connected with the at least one cord spool. A tilt cord is connected with the tilt cord pulley and with the shade such that the tilt cord and tilt cord pulley cooperate to tilt the shade. A drive shaft receiver is connected with the tilt cord pulley such that movement of the drive shaft receiver moves the tilt cord pulley. A counterbalance assembly including a negative gradient spring is connected to the drive shaft thereby providing an approximately constant tension on the tilt cord pulley.

Abstract: A single control input is realized with the use of a combination slat angle adjustment and window covering opening lift set structure which may be operated by a single wand. A three segment relative control logic is realized which includes movement within in the middle segment that controls the angle of the slats, and movement to and beyond the position where the slats are maximally angled in one direction results in at least one of opening (raising) or closing (lowering) of the slat set by “winding up” a lift cord set which may operate on the interior or exterior of the slat set.

Abstract: An apparatus for accumulating one or more lift cords used to lift an architectural opening covering comprises a base portion and a front portion having a diameter larger than a diameter of the base portion. The base portion has an opening configured to receive a rod that rotates in a first direction when the one or more lift cords are actuated to raise the architectural opening covering. The apparatus also comprises an outer surface having a plurality of grooves configured to receive at least one of the one or more lift cords when the one or more lift cords are actuated to raise the architectural opening covering and to allow the at least one of the one or more lift cords to accumulate on one or more of the plurality of grooves next to itself rather than on top of itself.

Abstract: A cord winding device for a Venetian blind includes a receiving unit, a resilient driving unit mounted in the receiving unit, a braking unit mounted in the receiving unit and adjacent to the resilient driving unit, and a unidirectional damping unit mounted in the receiving unit. Through cooperation between the braking unit and the resilient driving unit, during winding and unwinding of pull cords, a bottom rail can be descended slowly and stopped conveniently at any desired height.

Abstract: A cord drive mechanism to convert linear motion to circular motion for use in coverings for architectural openings. Various controls are used to provide a braking force on the cord. Some of the embodiments incorporate a capstan.

Abstract: The invention relates to a device (1) for winding up and unwinding raising cords of a screen, comprising: an elongate housing (2); a shaft (3) intended for rotation in the housing; a number of winding rollers (4) which are coaxially mountable on the shaft for winding up and unwinding the raising cords (5) and which are adapted for releasable fastening of the raising cords; a number of winding roller holders (6) for bearing-mounted support of the winding rollers, which winding roller holders are adapted to be received in the housing.

Abstract: A motorized window treatment controls daylight entering a space through a window and includes a covering material, a drive shaft, lift cords received around the drive shaft and connected to the covering material, and a motor coupled to the drive shaft. It also includes a spring assist unit for the motor providing a torque that equals the torque provided by the weight on the lift cords at a position midway between fully-open and fully-closed positions, minimizing motor usage and conserving battery life. A photosensor for measuring the daylight outside the window and temperature sensors for measuring the temperatures inside and outside of the window may be provided. The position of the covering material is automatically controlled to save energy, or may also be controlled in response to an infrared or radio-frequency remote control.

Abstract: A curtain structure without drawstring may include a curtain unit, a string scrolling base and an upper cover. The string scrolling base has a shell disposed in the base of the curtain unit, center portion of the shell having a shaft, both sides of which having a positioning shaft, and a line slot formed on both side walls of the positioning shaft, wherein upper periphery of rotating base has driving teeth having at least one groove, restricting guiding groove and arc rail groove on top surface thereof, and a driving unit is disposed on the positioning shafts, the driving unit having a rod to secure the string collecting bodies, and conjugating teeth are linked with the driving teeth of the rotating base; and an upper cover having a restricting groove corresponding to the rotating base, and a ball restricted in the groove of the restricting groove and the rotating base.

Abstract: A cord guiding device for a window blind includes a wheel holder, a guiding wheel and a cord-blocking unit. The guiding wheel is rotatably mounted on the wheel holder, and includes two protruding flanges that are spaced apart from each other, and has a wheel surface that is defined and disposed between the protruding flanges and that is adapted for a cord of the window blind to wind thereon. The cord-blocking unit is mounted on the wheel holder, and has a blocking surface that faces and is disposed proximate to the wheel surface of the guiding wheel for preventing the cord from slipping off the wheel surface and out from the protruding flanges.

Abstract: An apparatus for raising and lowering a covering member of a window covering includes a sliding base, a first biasing device, a connecting device, and a second biasing device. The sliding base is moved between a first position and a second position in a headrail. The first biasing device has two first biasing members to urge the sliding base toward the first position. The connecting device is moved between a third position and a fourth position in the headrail. The second biasing device has a second biasing member to urge the connecting device toward the third position. The second biasing member of the second biasing device is added at a middle of raising the covering member to help the covering member totally received close to or in the headrail.

Abstract: A rail anchor assembly for a corded window shade is disclosed. The rail anchor assembly can include: a spool including a first aperture for allowing a cord of the corded window shade to pass axially into an interior cavity of the spool; and a second aperture for allowing the cord to exit the interior cavity of the spool; and a retaining component for affixing an end of the cord to a component of the window shade other than the spool.

Abstract: A blind of the type having raise cords, by means of which the blinds can be raised and lowered, comprising a raise cord storage device attached to the building fabric adjacent to the blind, which retrieves and stores the raise cords.

Abstract: Disclosed is a blind cord winder integrating with stopping control to allow open/close operation of the cordless blind to lift or lower the cordless blind at any positions according to user's needs. The winder primarily comprises a spool installed inside a first compartment, a force-feedback mechanism, and a braking cushion mechanism installed inside a second compartment where the force-feedback mechanism is installed in a shaft cavity of the first compartment. The force-feedback mechanism includes a shaft sleeve and a volute spring. The braking cushion mechanism includes a friction ring, a friction spring, and a trigger sleeve. The friction ring is immovably installed inside the second compartment. The friction spring is tightly plugged into the friction ring and has an extrusion end for the trigger sleeve to trigger friction variation in a single directional rotation of the trigger sleeve.

Abstract: A cord-winding assembly of a window blind is disclosed. The cord-winding assembly includes a first spool and a second spool. The first spool has a first axis extending in an axial direction. A plurality of first grooves is formed on an outer periphery of the first spool. The first grooves are parallel to each other. Each of the plurality of first grooves has a circumferential length different from other first grooves. The second spool has a second axis extending in the axial direction. The first and second axes are parallel to each other. A plurality of second grooves is formed on an outer periphery of the second spool. The second grooves are parallel to each other.

Abstract: A window treatment roll-up device has: a support base, a rotation base, at least two power springs, a braking member and a control wheel. The support base comprises a first shaft, a second shaft, a third shaft and a fourth shaft, the third shaft and the fourth shaft are engaged with each other, a controlling rope wrapped around the second shaft, the rotation base is jacketed onto the second shaft. The control wheel is disposed on the fourth shaft and configured to be wrapped by a rolling rope. The braking member has a first end and a second end, the first end is tapered such that the braking member is cone-shaped; a spiral slot connecting between the first end and the second end is disposed on a surface of the braking member. The first end of the braking member and the power spring both jacket onto the third shaft.

Abstract: A spring drive system useful for window covers is disclosed, which comprises one or more coil spring drives or flat spring drives and the combination whose elements are selected from one or more of a group which includes (1) a band or cord transmission which provides varying ratio power transfer as the cover is opened and closed; (2) gear means comprising various gear sets which provide frictional holding force and fixed power transfer ratios; (3) a gear transmission which provides fixed ratio power transfer as the cover is opened or closed; (4) crank mechanisms; (5) brake mechanisms; and (6) recoiler mechanisms. The combination permits the spring drive force to be tailored to the weight and/or compression characteristics of an associated window cover such as a horizontal slat or pleated or box blind as the cover is opened and closed.

Abstract: A one-way damper unit of a pull cord device includes a unidirectional clutch that is disposed in a housing to form a liquid-filled gap therewith and that includes: a casing formed with deep and shallow groove portions; a main shaft having an insert segment extending into the casing and a connecting segment extending outwardly of the casing for connecting to a driven wheel; and a clutching member including a clutching body that extends into the groove and that has a cross-sectional dimension shorter than a distance between the insert segment and the deep groove portion, and longer than a distance between the insert segment and the shallow groove portion.

Abstract: A covering for an architectural opening has a horizontal movable rail supported by cords, with a variety of configurations which allow the movable rail to be moved up and down while concealing the cords.

Abstract: A window cover system includes an extendible window cover with a pair of lift cords. A lift cord pulley shaft is coupled to a pair of spaced apart lift cord pulleys. A spring drive unit has a beveled gear system with a first gear that is spring biased to resist rotation of first gear in one direction of rotation, and a second gear meshed with the first gear. The lift cord pulley shaft extends through the second gear and is configured to rotate therewith.

Abstract: A window blind assembly includes a securing seat, a blind unit, a blind control device and two cord guiding devices interposing the blind control device. Each of the cord guiding devices includes a wheel holder and a guiding wheel. The wheel holder includes a resilient arm unit and two holder walls. Each of the holder walls is formed with an engaging groove having a receiving portion and a constricted portion. The guiding wheel includes two axle portions rotatably and respectively received in the receiving portions of the engaging grooves in the holder walls, and a cord winding portion interconnecting the axle portions and permitting winding of a corresponding cord thereon.

Abstract: A spring counterbalance apparatus and method consists of a shade system with a torque profile, where the shade system is connected with a drive shaft. A first spring system is connected with the drive shaft where the first spring system is a standard wound spring system. A second spring system is connected with the drive shaft where the second spring system is a reverse wound spring system and where, in combination, the first spring system and the second spring system produce a counterbalance torque profile approximately equal to the shade system torque profile.

Abstract: An approach is provided for an apparatus for a blind is disclosed that comprises a rolling module and a control module. The rolling module is located above multiple tapes vertically spaced by a ladder cord. The control module is extended downwardly from the rolling module, and comprises an Epicyclic Gearing (EG) assembly, a spiral wand, a universal joint, a tilter and a control assembly. The EG assembly is configured for connecting the rolling module. The tilter is mounted at bottom of the spiral wand and is configured for controlling the flipping of the tapes. The control assembly is penetrated through the spiral wand, is supported by the tilter, and selectively moves up and down for rotating the spiral wand. The rolling module raises and/or lowers the tapes by the lifting cord according to the rotation of the spiral wand.

Abstract: A clutch for a roller blind. The clutch comprises a drive shaft operatively connected to a drive mechanism, an idle shaft releasably coupled to the drive shaft, and a drive spring. The drive mechanism imparts rotational movement to the drive shaft. The idle shaft is operatively connected to the tube of the roller blind such that rotation of the idle shaft causes rotation of the roller blind tube. The drive spring is operatively associated with the idle shaft and with the drive shaft such that rotation of the drive shaft in a first direction causes the drive spring to impart rotational movement to the idle shaft, thereby causing rotation of the roller blind tube. When the drive shaft is rotated in a second opposite direction the drive spring permits the drive shaft to rotate independently of the idle shaft.

Abstract: Disclosed is a control device for a cordless blind with willful stop at any positions according to user needs during switching operation. The control device primarily comprises a force-return mechanism, a shaft connector, and a braking buffer mechanism which are all installed inside a same housing. The force-return mechanism has a flat spring bevel gear and an elastic element. One end of the shaft connector is a transmission bevel gear meshed with the flat spring bevel gear. The braking buffer mechanism includes a friction ring and an impeding spring where the friction ring is immovably fixed inside the housing with a wear-proof annular inwall. The impeding spring is tightly plugged into the friction ring with an extrusion to prevent the rotation of the transmission bevel gear. Specifically, the shaft connector has a trigger to change the friction between the impeding spring and the friction ring.

Abstract: To reduce an opening and closing operation load in a venetian blind in which a lifting/lowering cord is disposed at a position offset from a central portion in a back and forth direction of a slat. At least one lifting/lowering cord is disposed along one vertical cord of front and back vertical cords and introduced into a head box from one side in a back and forth direction of the head box, and the other lifting/lowering cord is disposed along the other vertical cord and introduced into the head box from the other side in the back and forth direction of the head box. All the lifting/lowering cords introduced into the head box from the different sides in the back and forth direction of the head box are wound in the same direction by the lifting/lowering drums to which the respective ends of the lifting/lowering cords are connected.

Abstract: The invention relates to a cord winder (1) for a window-covering device, said cord winder including: a drum (7) for winding a cord (40), said drum being rotatable around a first rotationally symmetrical axis (A-A?); and a means (12, 13b) for guiding the cord to the winding drum, the winding drum being rotatably mounted in a holder (2). Said cord winder is characterized in that it includes a rotatable roller (14) that is mounted onto the holder along a second rotationally symmetrical axis (B-B?). Said cord winder is moreover characterized in that it includes a friction area (23) wherein at least one coil of the cord, wound onto the winding drum, is in contact with the rotatable drum.

Abstract: A retractable covering for an architectural opening includes a headrail in which a control system is mounted and a fabric suspended from the headrail. The fabric is mounted to be moved laterally between a rolled up retracted position and an extended position across the architectural opening. At least one roller about which the fabric can be wrapped is mounted at an end of the headrail for rotation about a vertical axis, and the system includes a flexible control element that is substantially horizontally disposed for moving the covering between extended and retracted positions.

Abstract: A window covering with improved controls enhances several aspects of window covering operation. A control mechanism provides a clutch module for selective locking and unlocking of a drive shaft used to retract and extend the shade element between storage and extended positions. The clutch module includes a reciprocator element that engages a key extending from an outer surrounding housing. A locking member between the reciprocator element and a coupling element carried by the drive shaft selectively locks and unlocks rotational coupling between the reciprocator element and the coupling element, thus selectively locking and unlocking the drive shaft. In a cushioning mechanism, a unidirectional dampening or frictional deceleration is provided for the drive shaft. The cushioning mechanism includes an impeller or rotor immersed in a cushion medium that impedes rotation of the rotor, and hence the drive shaft to which the rotor is coupled.

Abstract: A cordless blind contains a lift mechanism, such as one or more spring motors, one or more cord collectors and a lock mechanism. An operator device such as a cord or wand is connected to the lift mechanism and is movable relative to the bottomrail. When the bottomrail is a selected distance from the headrail a portion of the cord or wand will move away from the bottomrail. The selected distance corresponds to the height of the bottomrail at which it is difficult for an operator to reach the bottomrail. The released cord or wand will enable the user to operate a lock mechanism in the bottomrail or move the bottomrail.

Abstract: A spring drive system useful for window covers is disclosed, which comprises one or more coil spring drives or flat spring drives and the combination whose elements are selected from one or more of a group which includes (1) a band or cord transmission which provides varying ratio power transfer as the cover is opened and closed; (2) gear means comprising various gear sets which provide frictional holding force and fixed power transfer ratios; (3) a gear transmission which provides fixed ratio power transfer as the cover is opened or closed; (4) crank mechanisms; (5) brake mechanisms; and (6) recoiler mechanisms. The combination permits the spring drive force to be tailored to the weight and/or compression characteristics of an associated window cover such as a horizontal slat or pleated or box blind as the cover is opened and closed.

Abstract: A motorized venetian blind system for covering a window of a space comprising a blind drive unit having two motors to provide for independent control of a position of a bottom rail and a tilt angle of a plurality of slats of the blind system. The blind drive unit is operable to adjust the position of the bottom rail to a preset position, and to adjust the tilt angle of the slats to a preset angle in response to receiving a single digital message (e.g., a preset command). The blind drive unit is operable to automatically adjust the position of the bottom rail and the tilt angle of the slats to limit a direct sunlight penetration distance in the space to a maximum direct sunlight penetration distance, and to maximum a reflected sunlight penetration distance on a ceiling of the space, while minimizing occupant distractions.

Abstract: A shielding apparatus is provided in which operations of raising and lowering a middle rail and operations of raising and lowering a bottom rail can be performed independently from each other by means of a common operation cord. In a shielding apparatus equipped with an elevation apparatus configured to raise and lower a middle rail 3 and a bottom rail 5, whereby a shielding member 2, 4 can be pulled out in the vertical direction or folded in, the elevation apparatus comprises an operation cord 16 of an endless type hanging down from a head box 1, and selective operation means 13 configured to raise or lower the middle rail 3 through an operation of the operation cord 16 in one direction, and to raise or lower the bottom rail 5 through an operation in the other direction, wherein the selective operation means 13 is configured to push up the middle rail 3 by the bottom rail 5 so that the bottom rail 5 and the middle rail 3 can be raised together.

Abstract: A window cover system includes an extendible window cover that has a pair of lift cords. A lift cord pulley shaft is coupled to a pair of spaced apart lift pulleys. A spring drive unit is constructed of a beveled gear system with a first gear that is spring biased to resist rotation of the first gear in one direction of rotation, and a second gear meshed with the first gear. The lift cord pulley shaft is operably coupled to the second gear and is configured to rotate therewith. The spring drive unit has a single output and no input, and the single output is coupled to the first gear.

Abstract: A control device for a venetian blind, including a controller for controlling the venetian blind to draw and withdraw and a rotating handle for driving the controller to operate. The controller includes a first rotating member for driving a transmission shaft of the venetian blind to rotate and a second rotating member. The axis of rotation of the second rotating member and that of the first rotating member are orthogonal. The second rotating member is provided with a connection shaft connected with the rotating handle. The first rotating member is rotated coaxially with the transmission shaft to realize the drawing and withdrawing of the venetian blind. A venetian blind having the above control device for the venetian blind is further disclosed.

Abstract: A method for operating a window cover utilizes an extendible window cover having a first rail, a second rail and a pair of lift cords. The first and second rails of the window cover are movable relative to each other. According to the method, at least one of the first rail and the second rail is moved in a first direction to cause the lift cords to unwind from the lift cord pulleys, thereby rotating a lift cord pulley shaft and a set of gears. Further, at least one of the first rail and the second rail is moved in a second direction to cause the lift cords to wind on the lift cord pulleys, with the lift cord pulley shaft rotating in an opposite direction.

Abstract: Disclosed is a cordless blind assembly, comprising an upper frame rod with two blind cord winders disposed at two opposing sides, a retracting rod disposed beneath the upper frame rod, and two side guiding rails. A plurality of guiding components are disposed at the ends of the retracting rod. The driving cords from the blind cord winders connect to corresponding guiding components by going around both sides of the blind shading parts. The extended driving cords are hidden inside the side guiding rails where the guiding components can freely move inside the corresponding side guiding rails. Accordingly, the cordless blind assembly can avoid neck-strangling accidents to achieve easy DIY installation without breaking the function of the blind shading parts.

Abstract: Certain embodiments of a system for reducing backlash include a member geared for rotation in first and second directions. In various implementations, a first motor causes rotation in the first direction with an output biased to preclude space between mating gear components in the first direction, and a second motor, which is mechanically independent of the first motor, causes rotation in the second direction with an output biased to preclude space between mating gear components in the second direction.

Abstract: Disclosed is a cordless blind assembly, comprising an upper frame rod with two blind cord winders disposed at two opposing sides, a retracting rod disposed beneath the upper frame rod, and two side guiding rails. A plurality of guiding components are disposed at the ends of the retracting rod. The driving cords from the blind cord winders connect to corresponding guiding components by going around both sides of the blind shading parts. The extended driving cords are hidden inside the side guiding rails where the guiding components can freely move inside the corresponding side guiding rails. Accordingly, the cordless blind assembly can avoid neck-strangling accidents to achieve easy DIY installation without breaking the function of the blind shading parts.

Abstract: A one-way damper unit of a pull cord device includes a unidirectional clutch that is disposed in a housing to form a liquid-filled gap therewith and that includes: a casing formed with deep and shallow groove portions; a main shaft having an insert segment extending into the casing and a connecting segment extending outwardly of the casing for connecting to a driven wheel; and a clutching member including a clutching body that extends into the groove and that has a cross-sectional dimension shorter than a distance between the insert segment and the deep groove portion, and longer than a distance between the insert segment and the shallow groove portion.

Abstract: A string-guiding structure for a curtain-reeling device substantially has a string-guiding frame mounted at an entrance of a string-guiding wheel assembly to limit the string extended from the curtain-reeling device inside the string-guiding frame and to be wound on the string-guiding wheel assembly when the string is released or collected. Therefore, the string-guiding frame depresses the oscillation and swing of the string during operation to avoid the string being jammed in the gaps of the string-guiding wheel assembly.

Abstract: An automated control of a solar protection installation (INST), includes reflecting slats (B1, B2, B3) having parallel longitudinal axes, the slats having a face (F) provided with teeth (D) which flanks (F1), exposable to the light rays and called “useful” flanks, lie in parallel planes (P1, P2, P3, P4). The main direction of incidence (ASUN1; ASUN2) of the light rays on the slats is determined (CPU, CLK, ASUN) and a motor (MOT) is provided for tilting the slats at least substantially about their longitudinal axis. The slats are automatically tilted to orient the planes of the useful flanks depending on the main direction of incidence of the light rays.

Abstract: A hollow built-in window blind is provided. The window blind includes an outer glass (13a), an inner glass (13b), a spacing strip (14), a curtain (12), and a fixing device for the curtain. The curtain (12) is installed in a closed space enclosed by the outer glass (13a), the inner glass (13b), and the spacing strip (14). Furthermore, the spacing strip (14) has a step part to be connected with the curtain (12), and the fixing device includes an upper beam (1) with a projection, left and right frames (10a, 10b) with a projection respectively. The upper beam (1), left and the right frames (10a, 10b) are connected to the spacing strip (14) by the projections set on the step part of the spacing strip (14).

Abstract: In the present invention, flexible snap fit portions are provided on the base to engage directly into the upper beam so that the mounting of the base into the interior of the upper beam is easy. A cord spool is designed to be capable of continuing its rotation in a fitting member so that there is no limitation on the winding direction of the pull cord. Moreover, the fixing of either a connecting strap or a connecting string for connecting each slat of the window blind on a housing member is very easy. Therefore, easiness and handiness in operation can be improved in the overall implementation of the present invention.

Abstract: A bail lock for coverings for architectural openings wherein at least one of the bails defines a cord guide surface of changing front-to-back cross-sectional profile so as to define a cord passage between the inner and outer bails that varies from a relatively straight path that allows the cord to pass freely through, to a more tortuous path that applies substantial frictional force to the cord.

Abstract: A scrolling unit for blinds includes a scrolling unit having a main wheel, at least one sub wheel and a scrolling spring. The main wheel has a spool and a cable is wrapped to the spool. The scrolling spring has an inner end and an outer end. The inner end is securely wrapped to the main wheel and the outer end is wrapped to the at least one sub wheel. The scrolling force of the inner end is larger than that of the outer end. The cable is wrapped to a mandrel unit in the head box. The cable extends through the head box and is connected to the bottom bar. The blinds are connected between the head box and the bottom bar to which the cable is fixed. The bottom bar is cooperated with the scrolling spring regardless the weight of the bottom bar.

Abstract: A spring drive system useful for window covers is disclosed, which comprises one or more coil spring drives or flat spring drives and the combination whose elements are selected from one or more of a group which includes (1) a band or cord transmission which provides varying ratio power transfer as the cover is opened and closed; (2) gear means comprising various gear sets which provide frictional holding force and fixed power transfer ratios; (3) a gear transmission which provides fixed ratio power transfer as the cover is opened or closed; (4) crank mechanisms; (5) brake mechanisms; and (6) recoiler mechanisms. The combination permits the spring drive force to be tailored to the weight and/or compression characteristics of an associated window cover such as a horizontal slat or pleated or box blind as the cover is opened and closed.