Abstract:
An architectural covering, such as a blind, for use primarily over windows and doorways, includes of a plurality of separate composite vanes made of an opaque rigid material and a sheer material, if desired. Each composite vane can be manufactured as a flat, rollable laminated assembly of strips and joined or bonded at least substantially on a line along the length of the strip and substantially along one edge of one strip. Several different embodiments of the composite vane are disclosed. In one embodiment, the composite vane comprises a generally flat, unexpanded opaque material with individual pieces of sheer material attached to an edge of the vane. In another embodiment, a laminated composite vane comprises a pair of strips with the transverse width of one strip greater than the other strip to form a torque tube when edge-joining the strips. In yet another embodiment, the laminated composite vane includes a pair of strips of substantially equal width with a resilient insert strip having a non-flat cross section inserted into the torque tube. The resilient insert strip can assume a flat transverse form, but return elastically to the predetermined cross-sectional shape when removed from the roll or be inserted after each vane is cut to its final length. Any combination of the above-mentioned embodiments is possible to connect single or double sheets of sheer material to the edges of the vanes while enabling the vanes to be oriented vertically or horizontally.

Description:
CROSS NOTING TO RELATED APPLICATIONS 
     This application claims the benefit of provisional patent Application Serial No. 60/196,726, filed on Apr. 13, 2000, and provisional patent Application Serial No. 60/272,180, filed on Feb. 28, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to improved construction of an architectural covering for windows, and in particular to a vertical or horizontal blind with individual, narrow strips of sheer material and a vane having a strip element disposed therein. 
     2. Description of the Related Art 
     In many window or see-through door applications, it is desirable to control the amount of light admitted through the window or see-through door. For instance on bright sunny days in warm climates, the sun is too strong (and too hot) for comfortable working in offices, as well as being damaging to interior furnishings that may fade or become brittle. Typically, blinds are fitted, consisting of multiple slats of opaque material that can be individually rotated, in a coordinated manner, to block all or part of the light. When such slats are arrayed horizontally, the assembly is commonly called a “venetian” blind. 
     In large windows or doors, venetian blinds are difficult to raise completely, when needed for unobstructed viewing or to clean the glass behind. So, often a variant called “vertical blinds” is fitted, in which rotatable slats are hung vertically from their ends on a traverse mechanism with individual, coordinated rotating hangers. Vertical blinds have been most often used in commercial settings, where large windows are more common. In residential use, only patio doors and the like have commonly used these blinds. 
     Known vertical blinds commonly comprise elongated strips or slats of opaque material suspended vertically from an overhead traverse mechanism provided with individual, rotatable hangers. Some vertical blind products combine a sheer fabric with the rotatable, opaque vertical slats to provide diffusion of the light entering between the opaque slats, as well as adding privacy as a result of reduction in the clarity of view from the bright exterior into the interior of the building. 
     Examples of such combination vertical blinds are disclosed in U.S. Pat. No. 3,844,334 to Hyman and U.S. Pat. No. 5,638,880 to Colson et al. In Colson et al., the slats are integrated as stiffened fabric vanes permanently attached onto the expanse of covering sheer fabric. Tachikawa Company of Japan offers a vertical blind in which alternating vanes are sheer and opaque, but the hangers for the sheer vanes lack driven rotators, so that the sheer vanes tend to remain in planar alignment between adjacent opaque vanes when the latter are rotated toward their view-through position. This product lacks the aesthetically-preferred appearance of a continuous, billowed curtain, and gapping between the sheers and opaques is a problem because the sheers are free to rotate, though not forced to do so. 
     Even in smaller windows, where horizontal shading is practical, there has been a move toward light-diffusing systems. Translucent cellular shades and fabric venetian blinds have been devised using light-filtering materials to give light-diffusing properties to the window coverings. Of these, the fabric venetian blinds also present a sheer fabric covering that partly obscures the interior of a room from outside view, even when the major light-control elements are positioned for open view-through. This is a desirable feature for vertical blinds, too, and has been implemented in two ways: layering of a sheer curtain over a conventional rigid-vane vertical blind; and integrating the slats as stiffened fabric vanes permanently attached onto the expanse of the covering sheer. 
     The inventors of the present invention have recognized that a disadvantage of known opaque-with-sheer vertical blinds is that they use a large expanse of fragile sheer fabric to cover the entire opening. This requires a high degree of costly precision in fabric quality, handling, and cleaning to assure the delicate fabric remains free of visible flaws and damage throughout. The manufacturing equipment must be very large and costly (typically handling goods 90 to 150 inches in width), adding immensely to the final product cost and limiting the variety of colors and styles that can be produced. Waste in fabricating finished shades from such goods to fit various window sizes is significant (typically over 20% of raw goods, even with carefully optimized fitting). Installation, and even shipping, is extremely awkward with such large delicate sheers, and washing is almost impossible. Should one spot on the product become soiled or damaged, the entire product becomes waste. Still, consumers readily pay this price to achieve the soft, light-diffusing privacy and light control provided by such sheers with rotatable vanes. 
     SUMMARY OF THE INVENTION 
     In one embodiment of the invention, the architectural covering comprises a vertical or horizontal blind including an opaque strip or vane and a covering sheer strip, wherein the vanes are not expanded by any bowing or resilience. Each vane comprises an integrated composite of a relatively opaque portion and a laterally adjacent and relatively translucent portion having an upper end that is remote from its associated relatively opaque portion. The upper end is adapted to be secured to at least one of either the next adjacent hanger (typically carrying the next adjacent vane) or the free end of the relatively opaque portion of the next adjacent vane when such vane is installed in a window opening. This embodiment of the invention is especially useful for smaller windows and very flaccid sheers if the opaque strips are relatively heavy and stiff. 
     In another embodiment of the invention, an improved blind is disclosed for use primarily over vertically-glazed windows and doorways comprising a plurality of separate composite strips, wherein each composite strip is manufactured as a flat, rollable overlay assembly of strips. At least one of the strips could be transversely elastically bowed and attached along its free edge to another strip, forming a substantially rigid closed-perimeter element with an expanded cross-section for torsional and flexural strength. 
     The expanding of the section may be accomplished in a variety of ways. One way is by providing one strip having a transverse width greater than that of the one to which it joins, and by making the former strip resilient to bowing so as to create tension in the latter strip when the two are joined edge-to-edge after removal from a rolled to a straight condition. Another way the bowing may be accomplished is by inserting a separate resilient folded strip into the closed-perimeter element formed by edge-joining of strips in the basic composite, whereby the resilient strip is fitted into and through a substantial part of the length of the composite, after the composite is removed from a roll into a straight condition. Yet another way the bowing may be accomplished is by providing a resilient insert having a “V”, “C” or “S section form (or the like) that may be inserted into the closed-perimeter composite before rolling, whereby the resilient insert can assume a flat transverse form, but return elastically to the V, C, or S (or the like) when removed from the roll. 
     In one embodiment, each composite strip comprises at least a sheer or translucent portion and a relatively opaque portion; the two portions overlying in part, and joined or bonded at least substantially on a line along the length of the strip and substantially along one edge of one strip (typically the opaque). In another embodiment, each composite strip does not include the sheer translucent portion. As manufactured, strip portions are flat and overlaid, enabling rolling up of the composite. At final fabrication into a shade, cut lengths corresponding to the height (or width) of the window are assembled by bowing at least one strip (typically the opaque) and, if of the unequal transverse width type, adhering the previously unattached edge of that strip to the other strip, forming the bowed closed-perimeter section; and if of the insert type, either inserting the resilient strip or merely allowing the previously inserted element to re-assume its natural transverse form. The bowed strips are thereby made both torsionally-stiff and rigid against bending, although the resilient nature of the stiffening will allow bending past the limit of their elastic resistance, without permanent damage. 
     If used in a vertical orientation, the expanded composite strips are then hung by their top ends from an overhead rail with individual hangers (as commonly used for prior art vertical strip blinds), with attachment made to either the sheer, if present, or the opaque portions of the strips. In the preferred embodiment of the invention, the sheer portion is folded back across the opaque portion and then attached to the adjacent hanger, causing the sheer to span between adjacent opaque portions and giving the illusion of a continuous sheer curtain combined with light-controlling vanes. 
     If used in a horizontal application, the expanded composite strips may be assembled into conventional venetian blind ladder cord and actuator structures, with the sheer portions, if present, joined along the free edge, in either continuous or periodic points, to the adjacent strip; or they may be joined one to another with the sheers in tension between them, to provide alternate means of support and actuation (vane rotation). 
     It should be noted that the expanded element portion of the composite may also be made without an attached sheer, providing a lightweight, insulating, and optionally, light-diffusing replacement for conventional rigid-vane opaque vertical blinds or venetian blinds. It should also be noted that the opaque portion of each vane could be constructed of a single piece of material folded on itself, rather than from separate strips with two bond lines. 
     As described above, the present invention employs a novel strip construction that can provide the appearance and functions of the continuous sheer with rotatable vanes, but in a manner which requires far smaller and simpler manufacturing equipment; packages and installs much more easily; and is readily handled for cleaning or repair at minimal cost. The embodiments without sheer elements provide direct replacement for conventional solid vanes in horizontal venetians or vertical blinds, but with much lower mass and stowed bulk. The separate insert embodiments, both with and without sheers, further provide for convenient and inexpensive options in light blocking features, as the inserts can be, for instance, clear, milky, smoky, reflective, polarized, or opaque, without substantially altering the surface coloration or textures of the product, unlike conventional vertical or venetian blinds. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cutaway perspective view of an architectural covering, such as a blind, for a window in accordance with the invention in which an upper end of the blind is suspended from a conventional hanger and a lower end is secured by means of a conventional plastic tack. 
     FIG. 2 illustrates a top plan view of a conventional traverse type head rail provided with rotatable hangers with an opaque strip or slat suspended from each hanger. 
     FIGS. 3 and 4 show alternative means for securing the free or distal end of the sheer portion of a composite vane to the hanger of the adjacent composite vane. 
     FIG. 5 is a cross sectional view taken along the line  5 — 5  of FIG.  1 . 
     FIG. 6 shows a rollable laminate with an adhesive strip for a blind with an expanded vane according to a first embodiment of the invention. 
     FIG. 7 shows the assembled expanded vane of FIG.  6 . 
     FIG. 8 shows a rollable laminate with a receiving pocket for the blind with the expanded vane according to an alternate embodiment of the invention. 
     FIG. 9 shows the assembled expanded vane of FIG.  8 . 
     FIGS. 10-12 show another embodiment of a laminated opaque portion for use in the composite vane of the present invention. 
     FIGS. 13-15 show an alternate embodiment to the laminated opaque portion for use in the composite vane of the present invention. 
     FIG. 16 shows the rollable laminate of FIG. 10, but including a resilient strip or insert formed into a “V” cross-sectional shape. 
     FIG. 17 shows the rollable laminate of FIG. 11, but including a resilient strip or insert formed into a “C” cross-sectional shape. 
     FIG. 18 shows the rollable laminate of FIG. 12, but including a resilient strip or insert formed into an “S” cross-sectional shape. 
     FIG. 19 shows a cutaway perspective view of the assembled vertical blind of FIG. 18 with the sheer attached to the distal edge of the vane. 
     FIG. 20 shows a cutaway perspective view of the vertical blind of FIG. 18 with the sheer attached to the proximal edge of the vane. 
     FIG. 21 shows a cutaway perspective view of a ladder-supported sheer-faced horizontal blind including a vane with the resilient strip formed in an “S” cross-sectional shape. 
     FIG. 22 shows a cutaway perspective view of a ladder-supported horizontal blind of FIG. 7, but without the sheer. 
     FIG. 23 shows a sheer-supported horizontal blind including a vane with the resilient strip formed in an “S” cross-sectional shape. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1 and 2, the architectural device  10  of the invention will now be described. For purposes of the invention, the architectural device will normally be referred to as a window blind  10 . However, it will be appreciated that the architectural device  10  could be used for other purposes, such as on doors or to otherwise furnish the interior of dwellings. 
     The window blind  10  includes one or more vanes  12 , each vane  12  comprising an integrated composite of a relatively opaque portion or strip  14  (shown thicker) forming a light-controlling element, and a laterally adjacent and relatively translucent sheer portion or strip  16  (shown thinner) forming a light-diffusing element. The vane  12  can be formed by differential weaving or knitting; or by joining of dissimilar strips of opaque and sheer material by gluing, welding, stitching, or other attaching means along their common edge, whether abutted or lapped, as described below. Alternately, the sheer portion  16  can extend across the full width of the vane  12  with the opaque portion  14  laminated or painted (applied in fluid form) onto a portion of the sheer portion  16 . 
     In an alternate embodiment of the vanes  12 , the sheer portion  16  can be wider than the opaque portion  14  so that the sheer portion  16  can be folded over on itself for a portion of its width and joined to itself to form a tubular portion into which an opaque element can be fitted, as described below. 
     The window blind  10  broadly includes a conventional traverse type head rail  18  that could be suspended from a wall or ceiling (not shown) adjacent to a window opening (not shown). The head rail  18  is provided with conventional rotatable hangers  20  (schematically shown as circles in FIG.  1 ), with the opaque portion  14  suspended from each hanger  20 . A free or distal edge  22  of each sheer portion  16  is schematically shown as secured to the hanger  20  for the next adjacent composite vane  12 . The billowing of each sheer portion  16  between its edge  22  creates an illusion of a continuous curtain-like sheet of sheer material. 
     The window blind  10  includes a hole  26  near an upper end  28  of the vane  12  for mounting to the conventional hanger  20 . Typically, the hanger  20  includes opposed, staggered sides  30 ,  32  at a lower end  34  of the hanger  20 . One side  30  includes an outwardly extending projection  36  and the other side  32  includes a vertically offset outwardly extending projection  38 . To mount the vertical blind  10  to the hanger  20 , the upper end  28  of the vane  12  is passed between the opposed, staggered sides  30 ,  32  of the lower end  34  of the hanger  20 . As a result, the hole  26  of the vane  12  is captured by the staggered overlap formed by the projections  36 ,  38  of the two sides  30 ,  32  of the hanger  20 . The upper end  28  of each vane  12  may include a stiffening member  39  for providing structural reinforcement and increased wear resistance where the sheer portion  16  engages the staggered overlap of the two sides  30 ,  32  of the hanger  20 . The stiffening member  39  may be in the form of a strip of adhesive-backed stiff polyester film, for example, MYLAR®, commercially available from the DuPont Corporation. 
     As best shown in FIGS. 1 and 5, the lower ends  42  of adjacent vanes  12  can be loosely secured to each other by means such as a conventional plastic tack  40  which is pushed through the fabric and retained by the flexible, T-shaped end configuration of the tack  40 . This type of tack is commonly used to retain tags on fabric merchandise, such as clothing. One end of the opaque portion  14  and the sheer portion  16  may be joined to form a joint  52  along the vertical length of the vane  12 . 
     The construction of each vane  12  can take several forms, all consistent with the various embodiments of the invention. The vane  12  can be manufactured by differential weaving or knitting of the two zones of differing light transmission ability; by joining of dissimilar strips of opaque and sheer materials by glue, welding, stitching or other attachment means along their common edge, whether abutted or lapped; or the sheer can extend across the full width of the composite, with the opaque portion achieved by lamination or application of paint to a portion of the sheer. Still another alternative is to use a sheer strip having greater width than the final composite strip, so that the sheer is folded over upon itself to form a tubular portion into which an opaque element can be inserted. 
     As best seen in FIGS. 1 and 2, one aspect of the invention is that the sheer portion  16  is made of individual, narrow strips of sheer material, rather than one sheer for the entire vertical blind as in conventional blinds. It will be appreciated that the free or distal edge  22  of each sheer portion  16  can be secured to the next adjacent opaque portion  14  in a variety of different ways. For example, FIGS. 3 and 4 show alternative means for securing the free or distal edge  22  of the sheer portion  16  of the vane  12  to the hanger  20  for the adjacent vane  12 . In FIG. 3, the free edge  22  is looped around one end  24  of the opaque portion  14  of the adjacent vane  12 , and doubled back thereon for securing to the hanger  20  for that vane. In FIG. 4, the free edge  22  is doubled back on itself before being secured to the adjacent hanger  20 . 
     In the illustrated embodiment of FIG. 1, a problem may occur because the vertical blind  10  is constructed from uniformly thin, flexible vanes  12  that can be rolled during manufacture and for shipment. Unfortunately, the same properties give the vanes  12  a tendency to curl when hanging and to flex torsionally in response to forces from adjacent elements, rather than following the orientation imposed by the hangers  20  at the head rail  18 . This curling and flexing behavior may prevent full closure of the vertical blind  10  in the light-blocking position. 
     To correct this potential problem, the present invention is also directed in general to a novel vane construction that provides for a closed-perimeter torque tube. The torque tube may include an elastic, resilient expansion means that holds the vane open for straightness and torsional stiffness, but allows flat collapse of the vane for roll-up and transport. 
     FIGS. 6 and 7 show one embodiment of a laminated opaque portion  14  for use in the composite vane  12  of the invention. As shown in FIG. 6, a first resilient strip  44  is laminated along one edge or free end  51  to a second narrower strip  46 . The first and second strips  44 ,  46  can be made of any suitable flexible material that is light enough to be suited for use in a window covering and which does not break down under temperatures known to be prevalent in windows exposed to direct sunlight. The first and second strips  44 ,  46  may have a different thickness. For example, the first strip  44  may have a greater thickness than the second strip  46 . Suitable materials would include aluminum, plastic, fabric, or the like. 
     Attachments means, such as pressure-sensitive adhesive  48  with a temporary removable cover  50  is provided along the other edge or free end  53  of either the first resilient strip  44  or the second narrower strip  46 . The pressure-sensitive adhesive  48  can be of the type well known in the art. The first ends of the first resilient strip  44  and the second narrower strip  46  are joined together by gluing, welding, stitching, or other attaching means to form a joint  54 . To fabricate the laminated opaque portion  14  for use in the composite vane  12 , the first resilient strip  44  is bowed and attached to the second narrower strip  46  along their free edges or ends  53  to draw the second narrower strip  46  tight across its width. As shown in FIG. 7, the interior of the first and second strips  44 ,  46  of the opaque portion  14  of the composite vane  12  forms a torque tube. 
     FIGS. 8 and 9 show a laminated opaque portion  14 ′ according to an alternative embodiment of the invention. Similar to the opaque portion  14 , the first resilient strip  44  is laminated along one edge to the second narrower strip  46 . In addition, one end  51  of the first resilient strip  44  and the second narrower strip  46  are joined together by gluing, welding, stitching, or other attaching means to form the joint  54 . However, the opaque portion  14 ′ does not include the attachment means  48  at the other free end  53 , but rather includes a receiving pocket  56  made of a narrow strip  58  secured to the second strip  46  by an adhesive  60 . The adhesive  60  may be similar to the adhesive  48 . To fabricate the opaque portion  14 ′ for use in the composite vane  12 , the first resilient strip  44  is bowed to draw the second strip tight across its width until the free end  53  of the first resilient strip  44  is received in the receiving pocket  56 . The interior of the first and second strips  44 ,  46  of the opaque portion  14 ′ of the composite vane  12  forms a torque tube, as shown in FIG.  9 . 
     It will be appreciated that the opaque portions  14 ,  14 ′ will easily roll for storage prior to fabrication, but will form a torque tube when assembled to maintain the straightness and torsional stiffness of the opaque portions  14 ,  14 ′ of the composite vane  12 , unlike conventional vanes. 
     FIGS. 10-12 show another embodiment of a laminated opaque portion  14 ″ for use in the composite vane  12  of the present invention. In this embodiment, the opaque portion  14 ″ of the composite vane  12  includes a first strip  62  and a second strip  64  having substantially the same width as the first strip  62 , unlike the earlier opaque portions  14 ,  14 ′. The strips  62 ,  64  may be made of flaccid or resilient material and may have a different thickness. For example, the first strip  62  and/or the second strip  64  may be made of color fabric, or the like. Both edges or free ends  51 ,  53  of the two strips  62 ,  64  are joined together by gluing, welding, stitching, or other attaching means to form the joints  54 . 
     As shown in FIG. 10, the sheer portion  16  could be omitted in the composite vane  12  using the opaque portion  14 ″. However, the sheer portion  16  could be included in the composite vane  12  by attaching the sheer portion  16  at one edge  53  of the opaque portion  14 ″, as shown in FIG.  11 . The sheer portion  16  could also be included in the composite vane  12  by attaching the sheer portion  16  at the other edge  51 , as shown in FIG.  12 . In all configurations of FIGS. 10 through 12, the composite vane  12  incorporating the opaque portion  14 ″ can be easily rolled during manufacture and transport. 
     FIGS. 13-15 show an alternate embodiment to a laminated opaque portion  14 ′″ for use in the composite vane  12  in the present invention. In the alternative embodiment, the opaque portion  14 ′″ is formed of a generally U-shaped single strip  66  made of flaccid or resilient material having only one free edge or free end  51 . The single strip  66  may be made of color fabric, or the like. The free edge  51  of the opaque portion  14 ′″ is joined together by gluing, welding, stitching, or other attaching means to form the joint  54 . 
     Similar to the opaque portion  14 ″, the sheer portion  16  can be omitted in the composite vane  12  using the opaque portion  14 ′″, as shown in FIG.  13 . However, the sheer portion  16  could be included in the composite vane  12  by attaching the sheer portion  16  at an end  68  of the opaque portion  14 ′″, as shown in FIG.  14 . The sheer portion  16  could also be included in the composite vane  12  by attaching the sheer portion  16  at the free end  51 , as shown in FIG.  15 . In all configurations of FIGS. 13 through 15, the composite vane  12  incorporating the opaque portion  14 ′″ can be easily rolled during manufacture and transport. 
     Referring now to FIGS. 16-18, another aspect of the invention is that the opaque portion for the composite vane  12  may include a resilient insert strip or element  74  that is inserted into the torque tube formed by the laminated opaque portion for maintaining the straightness and torsional stiffness of the opaque portion  14 . For illustrative purposes, the strip  74  is shown inserted into the torque tube formed by the laminated opaque portion  14 ″. However, it will be appreciated that the strip  74  can be inserted into any of the previously mentioned alternative embodiments of the laminated opaque portion  14 ,  14 ′ and  14 ′″. In addition, the illustrative embodiment shown in FIGS. 16-18 shows the resilient strip  74  formed into a “V”, “C”, “S” cross-sectional shape, respectively. However, it will be appreciated that the resilient strip  74  could be any suitable non-flat cross-sectional shape that could maintain the straightness and torsional stiffness of the torque tube. 
     Preferably, the resilient strip  74  has substantially the same overall length as the laminated opaque portion  14 ′″. The resilient strip  74  can be inserted between the two strips  62 ,  64  after the two strips  62 ,  64  are assembled. However, it is possible to assemble the laminated opaque portion  13 ″ over the resilient strip  74  and be able to roll the blind  10  (especially the “C” and “S” cross-sectional form), provided the resilience of the material forming the strip  74  is sufficient to cause the resilient strip  74  to assume its expanded, straight form when unrolled. 
     When the composite vane  12  includes a sheer portion  16 , and particularly when the sheer portion  16  is attached to the adjacent hanger  20  in a top-actuated vertical blind  10  (for example, as shown in FIG.  1 ), the appearance and function of the blind  10  is affected by an attachment location of the sheer portion  16  with respect to the opaque portion  14 ″, for example, of the laminated composite vane  12 . In particular, if the sheer portion  16  is attached along an edge  76  of the opaque portion  14 ″ more distant from the billowed sheer face  78  of the blind  10 , then the sheer portions  16  tend to lie in contact with one another and enhance the illusion of a “continuous” sheet, as shown in FIG.  19 . If the sheer portion  16  is attached at the edge  80  of the opaque portion  14 ″ nearer the billowed sheer face  78  of the blind  10 , then the appearance of that nearer edge  80  effectively vanishes from sight as a separate element, as shown in FIG.  20 . As this is largely an aesthetic distinction, either is a preferred embodiment. It is also clear that attachment of the sheer portion  16 , if any, at other locations of the opaque portion  14 ″ can be practiced within the scope of the present invention, with varied appearances resulting from these different locations. 
     Even if the composite vane  12  omits the sheer portion  16  (FIGS. 10,  13  and  16 ), a composite vane  12  can result that can be attached to a conventional vertical blind head rail and hangers to produce a product very similar to conventional vertical blinds, except with added features. These include: 
     1) Greatly reduced weight of vanes, as the straightness comes from the novel construction rather than the mass of the vane or added weights at their bottom ends. Weight reduction reduces operating forces and wear on the hangers. 
     2) Improved closure when the vanes are rotated into contact for light-blockage, due to the superior straightness and stiffness of the torque-tube vanes; 
     3) Improved thermal insulation, due to the trapped air in the torque tube. Insulation can be further enhanced by including a light foam or fiber backing on the insert to reduce vertical air movement; 
     4) Selectable levels of light-control by changing the insert properties within a common, color-matched exterior finish. This feature might be useful as a seasonal change where sunlight is a problem in summer, but desirable in winter; 
     5) Aesthetic improvements in the airfoil shape of the vane and the superior straightness achievable with the new construction; 
     6) Easier installation, due to the lightweight of the vanes; 
     7) Washability of the vanes, which can be separated from their inserts and from the rest of the elements comprising the blind assembly, as needed for cleaning. 
     All of these advantages also apply to the sheer-attached versions shown in FIGS. 11,  12 ,  14 ,  15 ,  17  and  18 , which in addition, have: 
     1) Added privacy from sheer covering in view-through mode; 
     2) Unique washability for a sheer-vertical, as all others known have a continuous sheer sheet (some with permanently attached vanes), not smaller manageable strips. 
     The novel vane construction of the present invention can be applied to a horizontal blind as well as a vertical blind. In this application, the stiffness and low mass of the vane are key benefits, allowing for instance, increased spacings between ladder cord supports, though the torsional stiffness also prevents warping common to solid or flat-vane venetian blinds (typically, wood, vinyl, or aluminum). Most of the advantages in light-control variations and insulation apply as well to horizontal applications, though conventional horizontal actuation assemblies may prevent removal of individual vanes for cleaning. 
     In a conventional ladder-cord assembly of a horizontal blind, the composite vane  12  of the invention can be used with or without sheer portion  16  (FIGS. 21 and 22, respectively). However, if the composite vane  12  includes the sheer portion  16 , the sheer portion  16  must include a slit  82  to pass a ladder cord  84 . In this configuration, the operation is exactly like that of a conventional venetian blind. In particular, the ladder-cord assembly  10 ′ of the invention can be retracted from the window (not shown) by drawing the composite vanes  12  of the invention into a stack. 
     When the vanes  12  are stacked, a great advantage of the new composite vanes  12  of the invention is revealed. With conventional large-format venetian blinds (2 and 2.5 inch widths are currently popular), the thickness of the vanes, especially in wood or plastic is significant (typically 0.06 to 0. 15 inch thickness per vane). When these are pulled into a stack, the total height of the stack, equal to the sum of the vane thickness, can be a large part of the entire window height. With the composite vane  12  of the present invention, the individual vanes can have a thickness similar to conventional vanes when arrayed across the window, but the insert strip  74  easily allows the composite vane  12  to be collapsed further when pressed together in a stack between the head rail  18  and a bottom rail (not shown). Typical collapsed vane thickness of 0.03 inches is easily possible, giving a stack as much as 80% less than comparable rigid-vane venetian blinds (and approaching the compactness of the best, cellular shades). The lightweight stiffness of the new composite vanes  12  of the invention may also allow wider spacing of ladder cords for lower cost and improved aesthetics. Further, the improved composite vane  12  allows for large-format venetian blinds has several advantages as follows: 
     1) Lower total mass as compared to wood, metal or plastic solid vanes; 
     2) Extended spacing between supports because of an improved stiffness-to-weight ratio; 
     3) Tremendously smaller stacked height; 
     4) Light-diffusing options; 
     5) Fabric or printed finishes; and 
     6) Aesthetically-pleasing substantial thickness in the composite vanes when deployed. 
     Referring now to FIG. 23, an alternate embodiment of the ladder-cord assembly  10 ′ is illustrated. In this embodiment, the sheer portion  16  is included in the laminated opaque portion  14 ″ and extends from both edges of the opaque portion  14 ″. The illustrated embodiment including the composite vanes  12  with the insert strips  74  of the invention is an improvement over conventional fabric venetian blinds that include vanes with only flat flaps of fabric. In addition, the alternative embodiment provides insulation when closed, superior closure, and a more pleasing undulating surface when closed, as compared to conventional blinds having flat flaps of fabric. Further, the resilience of the insert strip  74  allows the composite vane  12  to flatten and roll (now in a transverse curling) around a roller  86  that is typically used in fabric venetian blinds instead of stacking (as with rigid venetian blinds). 
     It will be appreciated that the composite vane  12  can be manufactured by using a wide variety of techniques. For example, the composite vane  12  can be made of single piece of extrudable material, such as MYLAR® and the like, that can be extruded to form the torque tube of the invention. The composite vane  12  formed of MYLAR® material can have a wall thickness in the range of between about 0.003 to 0.010 inches for a composite vane  12  having a width of about 3 to 4 inches. It will be appreciated that the wall thickness of the composite vane  12  is roughly proportional to the width. Thus, the wall thickness can be thinner for a composite vane having less width, and vice versa. 
     One advantage of the composite vane  12  formed by extruding a single piece of material is that the composite vane  12  does not include the bond lines  54  as in the previous embodiments. In addition, the combination of the torque tube having a football-shaped cross section and the thickness of the composite vane  12  allows the composite vane  12  to have the torsional stiffness for enabling the composite vane  12  to maintain its cross-sectional shape while used as a vertical blind. In addition, the combination of the cross-sectional shape and thickness allows the composite vane  12  to collapse when stacked while used as a horizontal blind and to expand when not stacked. 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.