A window blind for privacy includes slats made of transparent material having an embossed pattern and a printed pattern thereon sufficient to decrease the transparency of the slat and obscure visibility through the slats while maintaining a high degree of translucency. The lift cord is positioned outside of the slats, and the slats are constructed to close without exposing significant voids there through that are not overlapped by an adjacent slat. A valance is formed from slats and overlaps spaces that may occur above and below the head rail.

BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention pertains generally to blinds for windows, doors and the like; and, more specifically, the invention pertains to blinds providing privacy during both day and night without blocking light passing through the blind. 
         [0003]    2. Description of the Related Art 
         [0004]    Coverings for windows, doors and other architectural openings serve a variety of purposes, both functional and aesthetic. Architects and consumers have placed increased emphases on the use of natural lighting in both workspaces and relaxation areas. Increased exposure to natural light, particularly during winter months of shortened daylight duration is believed by many to improve the attitude and well-being of individuals. Decreased reliance on artificial lighting can reduce energy requirements for a building. 
         [0005]    Simply providing additional windows to increase the amount of natural light entering a space is not always satisfactory. In urban settings, the external view through some or all of the windows may be undesirable. Even in suburban settings, building density can be high, with large houses placed relatively closely together on small property lots such that adjacent houses are literally in the shadows of each other. In these circumstances, aesthetically pleasing window coverings can enhance the appearance of a room by blocking the undesirable view outside the window. However, with known window coverings, completely blocking undesirable views through a window has been accomplished only by limiting significantly the light entering a room, thereby requiring dependence on artificial light sources. 
         [0006]    While uncovered windows providing natural lighting is often desirable, the bright light entering can become excessive on some days and for certain circumstances. Light diffusion to provide softened light to a room can be advantageous. Continued exposure to direct sunlight can fade fabrics on furniture and rugs, and can alter the appearance of photosensitive floorings. Protection against the damaging effects from direct, bright sunlight and ultraviolet radiation is desirable. 
         [0007]    With any window, whether large or small, privacy can be a concern in both daytime and nighttime hours. Balancing the desired features of allowing natural light to enter a room while also providing privacy in private areas such as bathrooms and bedrooms has been problematic, particularly at night when the outside is dark and the room is illuminated with interior lighting. To provide true privacy during both daylight and nighttime hours, known shades have been room darkening, made of highly opaque materials not allowing significant light to pass through. Accordingly, the benefits of natural lighting have not been available when a high degree of privacy is required. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention forms slats from transparent material that readily passes light therethrough, and modifies a surface of each slat to obscure visibility through the slat and thereby provide privacy even at night when the room is illuminated. Light transmission through the blind remains high even after treating to provide privacy. 
         [0009]    In one aspect thereof, the present invention provides a method of making a slat for a blind for an architectural opening. The method includes steps of extruding a slat body from a clear, transparent material, by forming a continuous strip having substantially parallel longitudinal edges and a width between the edges; and modifying at least one surface of the body to decrease the transparency of and obscure visibility through the body while maintaining translucency. 
         [0010]    In another aspect thereof, the present invention provides a window blind with a head rail and a plurality of elongated slats suspended from the head rail. The slats are bodies of transparent material having an embossed pattern on at least one surface thereof sufficient to decrease transparency through the slat and obscure visibility through the blind. 
         [0011]    In a further aspect thereof, the present invention provides a window blind with a head rail; a plurality of ladders suspended from the head rail, each ladder including uprights and rungs between the uprights; and a plurality of slats supported on the rungs, each slat being of transparent material having an embossed pattern on a surface thereof to decrease the transparency of the slat. At least some of the ladder uprights have loops thereon. A bottom rail is disposed beneath the slats, and a lift cord extends from the head rail through the loops and is connected to the bottom rail. 
         [0012]    In yet another aspect thereof, the present invention provides a window blind slat with an elongated body having edges along elongated sides thereof. The body is of substantially transparent material having an embossment including impressions of higher and lower formations substantially covering a surface of the body between the edges sufficient to reduce transparency of the slat and obscure visibility through the slat. 
         [0013]    In still another aspect thereof, the present invention provides a method of making a slat for a blind for an architectural opening. The method has steps of forming a slat body from a clear, transparent material; and embossing at least one surface of the body to decrease the transparency of the slat and obscure visibility through the slat while maintaining light transmission there through. 
         [0014]    An advantage of the present invention, in one form thereof, is providing a blind for windows, doors and other architectural openings that distorts visibility to provide privacy, yet allows the transmission of light therethrough to provide natural lighting in the room, without substantial room darkening. 
         [0015]    Another advantage of the present invention, in another form thereof, is providing a privacy blind that can be manufactured in a variety of different patterns and colors in a cost effective, economic manner. 
         [0016]    Still another advantage of the present invention, in still another form thereof, is providing a method to manufacture slats for blinds that provide privacy yet allow light transference. 
         [0017]    A further advantage of the present invention, in a further form thereof, is providing a window blind with structure enabling substantially complete covering of an opening, without significant holes, voids or spaces that can provide an unaesthetic appearance. 
         [0018]    A still further advantage of the present invention, in a still further form thereof, is providing a window blind with a bottom rail and a head rail valance that blend in appearance with the slats of the blind. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0020]      FIG. 1  is a perspective view of a privacy blind in accordance with the present invention installed on patio doors, with the blind shown in an open condition; 
           [0021]      FIG. 2  is a perspective view similar to that of  FIG. 1 , but illustrating the blind in a closed condition; 
           [0022]      FIG. 3  is an enlarged fragmentary perspective view of several slats of the blind shown in  FIGS. 1 and 2 , the view shown from the tops of the slats; 
           [0023]      FIG. 4  is an enlarged, fragmentary perspective view similar to that of  FIG. 3  but from an angle to better show the bottoms of the slats; 
           [0024]      FIG. 5  is an enlarged, fragmentary perspective view similar to that of  FIG. 3 , but illustrating the blind in a closed condition; 
           [0025]      FIG. 6  is an enlarged fragmentary view of the bottom rail for the blind shown in the preceding views; 
           [0026]      FIG. 7  is a fragmentary vertical cross-sectional view of one of the ladder portions of the blind shown in the preceding drawings; 
           [0027]      FIG. 8  is a fragmentary cross-sectional view of the blind shown in  FIG. 7 , the view taken on line  8 - 8  of  FIG. 7 ; 
           [0028]      FIG. 9  is a fragmentary cross-sectional view of the blind shown in  FIG. 7 , the view taken along line  9 - 9  of  FIG. 7 ; 
           [0029]      FIG. 10  is a flow diagram of a process for manufacturing blind slats in accordance with the present invention; 
           [0030]      FIG. 11  is a perspective view of a laminating roll used in the process shown in  FIG. 10 ; 
           [0031]      FIG. 12  is a perspective view of an embosser used in the process shown in  FIG. 10 ; 
           [0032]      FIG. 13  is a perspective view of a shaping fixture used in the process shown in  FIG. 10 ; and 
           [0033]      FIG. 14  is a cross-sectional view through a head rail and valance of a blind of the present invention. 
       
    
    
       [0034]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    Referring now to the drawings more specifically, and to  FIGS. 1 and 2  thereof in particular, a privacy blind  20  in accordance with the present invention is shown installed on a patio door assembly  22 . A privacy blind  20  in accordance with the present invention can be used advantageously on architectural openings of many types including windows, doors and the like, and is particularly advantageous in conditions where privacy is desired or required in combination with the transmission of light through the blind to provide natural lighting in the room. 
         [0036]    Privacy blind  20  includes a head rail  24 , a bottom rail  26  and a plurality of slats  28  therebetween. In  FIGS. 1 and 2 , only some of the slats  28 , but not all of the slats  28  are indicated with reference numbers. Slats  28  are suspended on ladders  30 , as will be described more fully hereinafter. For more narrow blinds  20 , two ladders  30  may be sufficient; and on wider blinds  20  three, four or more ladders  30  may be used. In the exemplary embodiment, three ladders  30  are provided. Also shown in  FIGS. 1 and 2  are ladder operator cords  32  for operating the ladders in known manner to tilt slats  28  between substantially horizontal positions as shown in  FIG. 1 , commonly referred to as an “open” condition, in which spaces  34  are provided between adjacent, substantially horizontal slats  28 ; and a “closed” condition as shown in  FIG. 2  in which the slats  28  are tilted to close spaces  34  with the individual slats substantially vertically positioned on edge. Ladders  30  can be adjusted to place slats  28  at intermediate positions between the fully open and full closed positions shown in  FIGS. 1 and 2 , respectively. 
         [0037]    Lift cords  36  are also shown in  FIGS. 1 and 2  for raising and lowering bottom rail  26 , causing slats  28  to stack thereon from the bottom up as is well known to those skilled in the art. Lift cords  36  have distal ends as indicated in  FIGS. 1 and 2 , and extend coextensively with ladders  30  from head rail  24  to bottom rail  26 , as will be described more fully hereinafter. 
         [0038]    Head rail  24  is mounted to patio door assembly  22 , with ladders  30  having slats  28  installed therein suspended from head rail  24  in known manner. Head rail  24  includes various operating mechanisms for tilting ladders  30 , guides for routing lift cords  36  to raise and lower bottom rail  26 , necessary cord locks for securing adjusted positions of the blind and the like. Various such mechanisms for head rail  24  can be used, and are well known to those skilled in the art. The particular types of operating mechanisms in head rail  24  are not relevant to the present invention and therefore will not be described in further detail herein. 
         [0039]    Bottom rail  26  in known blinds is a thin bar or tube forming the bottom of the blind and upon which the slats  28  stack as the blind is raised. In known designs, the bottom rail thereby forms an outline or demarcation at the bottom of the blind that appears differently from the slats there above. In accordance with the present invention, bottom rail  26  is formed of two slats  28 , designated as  28 A and  28 B in  FIG. 6 . Slats  28 A and  28 B are oppositely directed, that is they face in opposite directions to form an elliptical shape in cross-section. By using two slats  28 A and  28 B to form bottom rail  26 , the appearance of blind  20  beneath head rail  24  is consistent all the way through to the bottom edge of the blind. Slats  28 A and  28 B can be fastened one to another by end caps  38  at each end (one end cap  38  being shown in  FIG. 6 ), adhesive or other means. An advantage of using end caps  38  is providing a finished look and closing the end openings between slats  28 A and  28 B. 
         [0040]    As thus far described, exemplary blind  20  is a so-called “horizontal blind” with slats  28  horizontally disposed beneath head rail  24 , and a plurality of slats  28  arranged one beneath another between head rail  24  and bottom rail  26 . However, it should be understood that slats  28  of the present invention can be used also for so-called “vertical blinds” in which the slats are suspended vertically from one end beneath head rail  24 , with each slat extending from the head rail to the bottom of the blind, and a plurality of the slats arranged one beside another across the width of the blind. Commonly, in a vertical blind a bottom rail is not provided, and lift cords are not required. 
         [0041]    Slats  28  of the present invention are made of material and formed by a process whereby light is transmitted readily through each slat, but the translucency of the slat is increased to provide privacy. An exemplary process  50  for making slats  28  is shown in  FIG. 10 . Suitable materials for slats  28  include transparent or translucent plastics such as, but not limited to acrylics, clear PVC, polycarbonates and butyrate. 
         [0042]    Process  50  of the present invention includes a forming step  52 , a printing step  54 , an embossing step  56 , a shaping step  58  and a sizing or cutting step  60 . It should be understood that process  50  to be described hereinafter is exemplary for use with acrylics, and the details of the various process steps may vary depending on the material being used to form slats  28 . 
         [0043]    In forming step  52 , if the material being used is hydroscopic, a supply  62  of the material, normally pellets or other discrete particles of acrylic resin, for example, is treated preliminarily by pre-drying to remove moisture and prevent the formation of bubbles in the subsequent forming steps. Again, for the exemplary use of acrylic pellets, drying for approximately two and one-half hours at 175° F. has been found suitable for removing excess moisture. The pre-dried acrylic resin is vacuum loaded into a hopper  64 . From hopper  64 , the acrylic resin is gravity-fed to an extruder  66 , which in the exemplary embodiment is a screw extruder having a screw  68  therein. Screw  68  is suitable for use with acrylics and includes flights thereon decreasing in depth from the inlet end to the outlet end of extruder  66 . As known to those familiar with the extrusion art, as the acrylic material is conveyed forward by screw  68 , with the depth of the flight on screw  68  decreasing, the material is compressed increasingly. The increased compression generates shear heat in the material. The shear heat along with supplemental heat from external barrel heaters breaks down the acrylic pellets into a low viscosity melt. Temperatures should be kept sufficiently high to form a clear extrusion. Generally, higher temperatures provide clearer acrylic extrusions, and a melt temperature of approximately 420° F. has been found to be adequate for desired levels of clarity. A die  70  is provided at the front of extruder  66 , and the melted acrylic is forced through die  70  as the material emerges from extruder  66 . The emerging material forms a continuous web or strip  72  having the general shape of die  70 , again has well understood by those familiar with the art. Standard slat sizes can be formed in thicknesses from approximately 0.038 inch to approximately 0.150 inch and in widths between the edges of strip  72  from approximately 1.5 inch to approximately 3.7 inches. 
         [0044]    Strip  72  advances from extruder  66  to printing step  54  wherein option patterns, designs and colors can be applied to a surface of the strip. It should be understood that between extruder  66  and printing step  54 , strip  72  may require support by use of air jets, rollers or the like. 
         [0045]    Printing step  54 , in the exemplary process shown, is a laminating or transfer printing process in which ink in a desired pattern, which can be specifically designed or random, is transferred to a surface of strip  72 . In a suitable transfer process, a Mylar or other web  74  ( FIG. 11 ), having an ink pattern  75  thereon, is provided as a supply roll  76  from which a continuous feed thereof passes through an ink-transfer station or laminator  78  including opposed rollers  80 ,  82  forming a transfer nip  84 . The term “ink” as used herein is intended to include inks and paints of various types as well as pigmented solids or other colorants that can be applied to strip  72 . Acrylic strip  72  and Mylar web  74  pass together through nip  84 , wherein the ink pattern  75  on web  74  is released from web  74  and transferred to the surface of strip  72  under the application of pressure in nip  84 . After the ink is released there from, web  74  is accumulated on a take-up roll  86 . 
         [0046]    Printing step  54  is performed relatively close to extruder  66 , but spaced sufficiently therefrom so that some cooling of strip  72  occurs before strip  72  enters laminator  78 . If strip  72  is too hot, Mylar web  74  can wrinkle or melt. However, laminator  78  should not be so far from extruder  66  that strip  72  is cooled excessively. Strip  72  should remain sufficiently hot that proper ink transfer occurs from Mylar web  74  to extruded strip  72 . Generally, if strip  72  at the exit from transfer nip  84  maintains an exit temperature at about 300° F. sufficient ink transfer occurs without wrinkling in Mylar web  74 . 
         [0047]    Printing step  54  can be performed using ink pattern  75  provided on web  74  in specific designed patterns of objects or things such as flowers, leaves or the like. Further, ink pattern  75  for printing step  54  can be provided in desired geometric or random patterns. Further, ink pattern  75  can be provided in discrete lines or shapes or can be provided as a continuous colored band or block for full color coverage of the entire surface of strip  72 , or of discrete portions thereof such as bands or stripes. Single solid colors or multi-colors can be used as ink pattern  75 . Artistic and aesthetic concerns can be met by virtually limitless printing configurations. However, it should be understood that printing step  54  also can be omitted, and a clear unprinted strip  72  can be passed to subsequent processing. While a laminating or transfer process is shown in the exemplary process  50 , other coloring or printing processes also can be used, such as, for example and not limitation, wash coat, gravure or tip printing. Further, instead of or in addition to printing step  54 , color can be added to strip  72  during the extrusion or other forming process by the addition of colorants to the feed material. 
         [0048]    From printing step  54 , the printed strip  72  advances to embossing step  56  wherein physical modifications are made to a surface of strip  72  that decrease the transparency of strip  72  while retaining a high level of translucency. An embosser  90  includes an embossing wheel  92  and a backing wheel  94 . Embossing wheel  92  has surface configurations  96  in the form of discrete projections to create a surface topography or embossment of impressions  98  ( FIG. 12 ) on strip  72 . Impressions  98  are formed of sufficiently varying height and depth, and sufficiently close to one another so as to reduce the transparency of strip  72  while retaining a desired level of translucency to provide desired privacy features regarding visibility through the slat together with a desired level of light transfer through the slat. Decreased transparency, making the strip translucent, is achieved with deeper impressions more closely spaced together. For greater privacy, the embossment should substantially cover the entire surface between edges of strip  72 . The temperature of strip  72  in embosser  90  should remain sufficiently high for suitable penetration depth in the embossing step  56 , and for subsequent handling to be described. However, the temperature of strip  72  at embossing step  56  should not be so high as to cause material flow after embossing, which can distort the embossing pattern and degrade embossing detail. It has been found that an exit temperature for strip  72  as the strip emerges from embosser  90  of about 250° F. works well together with a nip pressure of about 1000 psi between embossing wheel  92  and backing wheel  94 . Various patterns can be used in embossing step  56  to provide desired aesthetic effects as well as performance. 
         [0049]    From embossing step  56 , web  72  advances to shaping step  58  wherein both cooling and shaping occurs. A shaping table  100  provides a crown across the width of the slat, from one side edge to the other side edge. A crown of approximately ¼ inch has been found satisfactory. Crowning plates  102  ( FIG. 13 ), as known to those skilled in the art, can be used above and below strip  72 . Crowning improves rigidity of the slat, and may be desirable for longer slats; however, flat slats without crowning also can be used. Maintaining a temperature of approximately 250° F. at the exit of the embosser not only improves embossing but also ensures sufficient flexibility in an acrylic strip  72  for shaping. 
         [0050]    Fans  104  provided above and/or below strip  72  force air against and around the strip from opposite sides to promote cooling. Relatively slow, even cooling is preferred to prevent warping or curling. While two fans  104  are shown, it should be understood that a series of fans  104 , both above and below strip  72 , can be used. 
         [0051]    Upon completion of final shaping and cooling, strip  72  is passed through a puller  106  to cutting step  60  wherein desired lengths for slats  28  are cut. Cutting step  60  can include operating a saw, knife or other cutting means  108  for severing strip  72  in desired lengths for subsequent use. Various types of encoders and other measuring or length determining systems and processes can be used to ensure consistent desired lengths for all slats  28  emerging from cutting station  60 . 
         [0052]    As understood by those familiar with extrusion processes, puller  106  near the end of process  50  is used to move strip  72  through out the process. Pullers well known in the industry include belt pullers and other types that can be used in the present process. Desirably, puller  106  will not mark or otherwise disfigure the completed product. As those skilled in the art of extrusion processes will readily understand, puller  106 , embosser  90  and laminator  78  are synchronized to the same speeds to maintain constant tension in strip  72 . 
         [0053]    Formed in this manner, slats  28  are translucent and light diffusing from the embossment formed therein. The transparency thereof is decreased to provide privacy by obscuring visibility through the slat, but the slat remains translucent to allow light to pass there through. 
         [0054]    Ladders  30  have a pair of uprights  110 ,  112  and a series of rungs or cross-members  114  extending therebetween. Slats  28  are supported on rungs  114 . Differential vertical movement between uprights  110 ,  112  causes rungs  114  to assume different angular positions, from substantially horizontal as required for the open position of blind  20  as shown in  FIG. 1 , to the severely angular, almost vertical position in which the slats are nearly vertical on edge as shown in  FIG. 2 . Since slats  28  are supported on rungs  114 , slats  28  move together with rungs  114  as the rungs are moved between various angular positions. 
         [0055]    To retain proper lengthwise positioning of slats  28  within ladders  30 , notches  116 ,  118  are provided on the front and back edges of slats  28  respectively, to receive therein the uprights  110 ,  112 . It should be understood that while notches on the front and back are shown, notches on only one or the other edge also can be used, perhaps alternating with notches for others of the ladders  30  when multiple ladders are used. 
         [0056]    At spaced positions along the lengths thereof, ladder uprights  110 ,  112  are provided with loops  120  positioned outwardly. Lift cords  36  extend through loops  120  from head rail  24  to bottom rail  26 . Lift cords  36  can be provided on the front and back of each ladder  30  or can be provided on one or the other. When multiple ladders and lift cords are used, each ladder can include two lift cords as shown in  FIG. 3 , or one ladder can have a lift cord  36  on the front edge thereof and another ladder  30  can have a lift cord  36  at the back edge thereof. Further, with multiple ladders, each ladder can be provided with one or two lift cords as described, or some ladders can be used without lift cords when sufficient lift cords are provided on others of the ladders. By providing the lift cords away from the slats  28 , slats  28  are continuous without interruption except for the shallow notches  116 ,  118 , and when Blind  20  is closed as shown in  FIG. 5  no holes or openings extend through one slat that are not covered by an overlapping slat. As shown in  FIG. 5 , notches  116  are covered by the slat there behind, so that no unobstructed light passes therethrough. 
         [0057]      FIG. 14  shows a valence  130  for head rail  24 . A plurality of head rail clips  132  are used connected to head rail  24 . Only one head rail clip  132  is visible in the cross-section shown in  FIG. 14 ; however, it should be understood that two or more clips  132  will be used. Each clip  132  includes a spring arm of  134  for connecting to head rail  24 , a body portion  136  projecting in front of head rail  24  and first and second holding arms  138 ,  140  to hold first and second overlapping slats  28 C and  28 D. Slats  28 C and  28 D are similar to slats  28 ,  28 A and  28 B. Accordingly, valance  130  provides a consistent color and appearance as in the main portion of blind  20 . Further, uppermost most slat  28 D overlaps and covers any space at the top of head rail  24 , and lower slat  28 C overlaps and covers any space between the bottom of head rail  24  and the uppermost slat  28  in blind  20 . 
         [0058]    While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.