Abstract:
A blinds slat has a major portion being strips of bamboo and a minor portion being one or more pairs of wooden strips that are located at or near opposite side extremities of the slat. The resulting composite bamboo and wooden slat has exemplary resistance to warping and other deleterious effects of exposure to sun and moisture. Also disclosed is a method for producing the slats that is particularly advantageous in avoiding environmental harm, in that only small amounts of wood are used.

Description:
BACKGROUND  
         [0001]    The present invention relates to window shades, and more particularly to such shades having bamboo slats. the slats themselves, and methods for making the slats.  
           [0002]    Slats of conventional Venetian blinds are typically made of thin metal or plastic strips. the use of either of these types of material presents significant environmental risks, in the form of pollution, depletion of non-renewable resources, damage to surface features, and various combinations thereof. Wood has also been used for making the slats of blinds, but this material is increasingly scarce and expensive, particularly when selected and processed for uniformity, dimensional stability, and appearance.  
           [0003]    As a result of these and other considerations, bamboo has also been used to fabricate slats. The use of bamboo for the slats of blinds provides significant advantages in preservation of the environment, in addition to the potential of improved appearance. However, there are significant problems to be overcome, such as susceptibility to impact damage and weathering, and dimensional instability. See, for example, U.S. Pat. Nos. 5,896,903 and 6,192,949 to the present inventor, and U.S. Pat. No. 6,098,680 to Chen, each of these patents being incorporated herein by this reference.  
           [0004]    Although some of the above difficulties are addressed in the patents referenced above, the bamboo slats as used in Venetian blinds of the prior art are still not entirely satisfactory in that they exhibit dimensional instability and weathering due to the effects of exposure to the sun and moisture, and in at least some cases they are not economical to produce.  
           [0005]    Thus there is a need for slats of bamboo and blinds made therefrom, as well as a method for producing such slats, that overcomes the disadvantages of the prior art.  
         SUMMARY  
         [0006]    The present invention meets this need by providing blinds slats that are particularly resistant to warping and other forms of deterioration when subjected to repeated exposure to the sun and moisture, the slats being formed as composites having a major proportion of bamboo and a minor proportion of wood. In one aspect of the invention, a composite blinds slat includes a bonded plurality of bamboo strips forming a center portion of the slat; and a pair of wooden strips bonded to opposite edges of the center portion, the wooden strips being flush with opposite sides of the center portion. Each of the bamboo strips and/or each of the wooden strips can form portions of opposite major faces of the blinds slat. The major faces can be planar and parallel. As used herein, the terms “wood” and “wooden” are exclusive of bamboo.  
           [0007]    The composite blinds slat can also include a further pair of bamboo strips bonded opposite the pair of wooden strips to form respective edge portions of the blinds slat. The edge portions can be shaped to form respective rounded edge margins of the blinds slat. Also, or alternatively, each of the edge portions can include a pair of bamboo strips.  
           [0008]    The wooden strips can include or be formed of basswood. Also, a plurality of clearance passages can be formed between opposite major faces of the blinds slat for locating the slat in a blinds assembly. Further, the invention provides a blinds assembly including a plurality of the blinds slats having the clearance openings.  
           [0009]    In another aspect of the invention, a method for forming a composite blinds slat includes providing a plurality of bamboo strips having adhesive coatings thereon; providing a plurality of wooden strips; bonding a pair of the wooden strips together with the bamboo strips such that a majority of the bamboo strips extend in parallel adjacency between the wooden strips; and smoothing opposite surface extremities of the bamboo and wooden strips to form flush and continuous major faces of the composite blinds slat. The method can further include forming a plurality of clearance passages between the major faces of the slat. The bonding can further include bonding an additional pair of the bamboo strips opposite the pair of wooden strips to form respective edge portions of the blinds slat.  
           [0010]    The providing can of respective pluralities of bamboo and wooden blanks, the bonding can be of the respective bamboo and wooden blanks to form a block having a majority of the bamboo blanks extending in parallel adjacence between a pair of the wooden blanks to form a block, the method further including parting the block to form a plurality of composite blanks, and the smoothing can be of opposite side of the blanks to form respective major faces of a plurality of blinds slats. Further, the bonding can be of a larger number of the respective bamboo and wooden blanks to form a composite plank, with the parting further including separating the plank into a plurality of composite blocks, thereby to form a multiplicity of the blinds slats. 
       
    
    
     DRAWINGS  
       [0011]    These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings, where:  
         [0012]    [0012]FIG. 1 is an oblique perspective view of a composite wood and bamboo blinds slat according to the present invention;  
         [0013]    [0013]FIG. 2 is a lateral sectional view of the slat of FIG. 1;  
         [0014]    [0014]FIG. 3 is a pictorial diagram of a portion of a process for making the blinds slat of FIG. 1;  
         [0015]    [0015]FIG. 4 is a flow chart for the process of FIG. 3; and  
         [0016]    [0016]FIG. 5 is a perspective elevational view of a blinds assembly incorporating slats in the configuration of FIG. 1.  
     
    
     DESCRIPTION  
       [0017]    The present invention is directed to slats for Venetian blinds, assemblies incorporating the slats, and a method for producing the slats as composites of bamboo and small amounts of wood to form a product that is particularly resistant to the deleterious effects of weathering. With reference to FIGS.  1 - 5  of the drawings, a blinds slat  10  according to the present invention includes a plurality of bamboo strips  12  and a parallel-spaced pair of wooden strips  14  that are located at or spaced slightly inwardly from respective opposite side edge margins  16  of the slat  10 , the slat also having opposite major faces  18  and opposite ends  20 , a plurality of mounting and/or alignment passages  22  extending between the faces  18 . Preferably at least a center portion  24  of the slat  10  includes a plurality of the bamboo strips  12 , at least one of the strips  12  extending in respective edge portions  26  between each of the wooden strips  14  and the corresponding side edge margin  16 . In the exemplary configuration shown in FIGS. 1 and 2, the edge portions  26  each include two of the bamboo strips  12 , the outermost being designated  12 E and having a rounded contour forming the corresponding side edge margin  16 . It will be understood that the center portion  24  as well as the edge portions  26  can each contain any number of the bamboo strips  12 , although the center portion  24  normally contains several of the bamboo strips  12 . It will be further understood that the blinds slat  10  can contain additional ones or pairs of the wooden strips  14 , whether the strips of respective ones and/or pairs of the wooden strips  14  are joined or separated by one or more of the bamboo strips  12 .  
         [0018]    It has been unexpectedly discovered that only a small amount of wood material, when properly located, is effective for significantly improving the dimensional stability and resistance to weathering of the blinds slats  10  when assembled in Venetian blinds. A suitable material for the wooden strips  14  is basswood. Other suitable materials include, but are not limited to, oak, mahogany, birch, and maple.  
         [0019]    [0019]FIG. 2 shows a composite plate  30  which can be prepared according to the process for forming a bamboo plate as described in the above-referenced &#39;949 patent, except that skinless bamboo blanks  32  of the plate  32  are combined with pairs of wooden blanks  34  in a manner corresponding to a desired configuration of the blinds slats  10  to be produced therefrom. More particularly, the bamboo blanks  32  and the wooden blanks  34  are subsequently split to become respective bamboo strips  12  and wooden strips  14  of plural slats  10 . The composite plate  30  can include a single complement of strips or, preferably, multiple such complements which may be separated by respective dummy slats  36  as shown in FIG. 2. FIG. 3 shows the composite plate  30  having been separated such as by cutting away the dummy strips  36  to form respective composite blocks  38 . It will be understood that the dummy strips  36  can have any suitable thickness in that the severed composite blocks  38  (or the subsequently formed composite slats  10 ) can be trimmed to a desired width in a manner removing any remaining portions of the dummy strips  36 . Alternatively, the dummy strips can be omitted, the bamboo strips  32  that will form the side edge margins  16  of the finished slats  10  being of sufficiently increased width to allow for cutting the plate  30  into the blocks  38 . In another alternative, the plate  30  can be formed with adhesive material being omitted from facing sides of the bamboo strips  32  that will form the edge margins  16 . FIG. 4 shows one of the composite blocks  38  having been separated into a plurality of composite blanks  40 , each of the blanks  40  being subsequently finished in any suitable manner to form desired contours of the side edge margins  16  and the passages  22 , and to apply suitable protective and/or decorative coatings thereto. It will be understood that the lengths of the composite plate  30  and/or the composite blocks  38  can correspond to or be greater than a desired finished length of the blinds slats  10 , or multiples thereof. Further, some of the bamboo strips  32  (and even, in appropriate cases, some of the wooden strips  34 ) can be plural members placed end-to-end, and some such members can have lengths being than that of the blinds slats  10 , in which case the slats  10  will be formed with one or more end-to-end splices in some of its strips. Moreover, such splices can be beveled, square, or having any other desired configuration.  
         [0020]    With particular reference to FIG. 5, a process for forming blinds slats  10 , designated composite blind slat forming method  50 , includes a prepare bamboo blanks step  52  wherein skinless bamboo strips are formed and treated as described up to Col.  2 , line  32 , of the &#39;949 patent to provide the bamboo blanks  32 . Also, a smaller number of the wooden blanks  34  are prepared in any suitable manner and coated with adhesive in a prepare wooden blanks step  54 . Next, the blanks  32  and  34  are combined and loaded into a suitable press (not shown) in a load press step  56 , followed by a bonding step  58  in which the composite plates  30  are formed, an exemplary configuration thereof being that shown in FIG. 2. The bonding can be performed at room temperature, and at a pressure of between approximately 45 Kg/cm 2  for approximately 40 minutes, using a suitable resin and hardening agent.  
         [0021]    Each composite plate  30  is then separated into the plural composite blocks  38  (as shown in FIG. 3) in a first parting step  60 , and the blocks  38  are themselves separated into the plurality of composite blanks  40  (as shown in FIG. 4) in a second parting step  62  by suitable means such as sawing.  
         [0022]    The blanks  40  are then subjected to an edge forming step  64  wherein the contours of the side edge margins  16  are shaped by suitable means such as milling or planing, a surface forming step  65  wherein the major faces  18  are smoothed by suitable means such as sanding, planing and/or grinding, and a hole forming step  66  wherein the passages  22  are formed by suitable means such as drilling or punching. Also, suitable base and/or face coatings are applied in a finishing step  68 , thereby to complete the blinds slat  10  of the present invention. It will be understood that the various forming and finishing steps are optional depending on the desired configuration of the slats  10 , and they can pe performed in any suitable order. Also, the first and second parting steps are optional, although they are preferred for facilitating high production rates of the finished blinds slats  10 .  
         [0023]    [0023]FIG. 6 shows a Venetian blinds assembly  70  incorporating composite slats  10  as shown in FIG. 1 and described above.  
         [0024]    Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. For example, the slat can incorporate one or more additional wood strips. Therefore, the spirit and scope of the appended claims should not necessarily be limited to the description of the preferred versions contained herein.