You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to window blind assemblies and, more particularly, to a blind assembly particularly well adapted for mounting over doorlights.  
           [0002]    Window units incorporating blinds are well known in the prior art. These units include two panes of glass an a blind assembly sandwiched between the two panes. The blind assemblies include mechanisms both for raising and lowering the blinds and for tilting the blind slats. The units include slides or knobs or handles coupled to the mechanisms and accessible from the outside of the unit. When a window unit is especially designed or adapted for installation in a door, the unit is referred to as a doorlight.  
           [0003]    Because it is difficult, time-consuming and costly to replace existing doorlights with doorlights having integral blinds, retrofit assemblies have been developed for retrofitting blinds over doorlights. These retrofit assemblies include a frame that supports both a pane of glass and a blind assembly. The frame is attached over the frame of the existing doorlight such that the blind assembly is sandwiched between the pane of the assembly and the existing doorlight. Screws are typically used to attach the assembly to the doorlight and/or the door. One particularly good example of a retrofit assembly is illustrated in U.S. Pat. No. 5,996,668 issued Aug. 14, 1998 to DeBlock et al.  
           [0004]    Retrofit units are superior to the simple attachment of a blind assembly first because the retrofit units protect the blinds from wear and tear and encase the cords of the blind assembly. Freely hanging cords can be a hazard to children and pets. Second, the retrofit unit confines the blind and prevents the blind from swinging into the door as the door is opened and closed or during high winds, thus preventing damage to the blind and the door. Finally, the encased window blind is more aesthetically pleasing than a traditionally hung window blind; and the encased blind requires cleaning less frequently, if ever.  
           [0005]    Despite the advantages of these systems, there is room for improvement. First, the cords in the units can become tangled if the blind is permitted to free fall within the unit and/or if the unit is inverted (e.g. prior to or during installation). Second, the mechanism of the units often are visible along the sides or edges, contributing to an unsightly appearance. Third, the units require a considerable amount of time to install. Fourth, the fasteners for the units leave permanent marks (e.g. holes) in the face of the door, which are unsightly if the retrofit unit is removed. Fifth, stocking of units of blinds having different colors creates a significant inventory issue. Sixth, replacing a blind in a unit is extremely difficult, if not impossible. This can be a problem if a consumer wishes to change the color of the blind assembly or if a defective blind must be replaced. A consumer usually replaces the entire unit if they wish to change the color of the blind.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention overcomes the noted problems by providing a an improved retrofit doorlight blind assembly having several novel features.  
           [0007]    In a first aspect of the invention, the operator mechanism for the raise/lower feature includes gears and a toothed drive belt to ensure positive engagement of the drive mechanism. More particularly, a first gear drives the blind operator rod; a second gear provides an idler, and the toothed belt is looped around the two gears to provide the driving mechanism.  
           [0008]    In a second aspect of the invention, the frame includes multipurpose blind guides. First, the guides have a C-shaped section that surrounds the edges of the blind to guide the blind during raising and lowering. Second, the guides secured the glass panel within the frame. Third, the guides hide the mechanism from view. And, fourth, the guides reinforce the frame.  
           [0009]    In a third aspect of the invention, the assembly includes an improved mounting system for mounting the retrofit assembly over a doorlight. More specifically, the mounting system includes a top bracket that is secured behind the top of the doorlight frame on which the assembly is easily hung. The system also include latches that lock behind a lower portion of the doorlight frame to secure the bottom of the assembly.  
           [0010]    In a fourth aspect of the invention, the blind snap-fits into the assembly frame so that the blind is easily attached to and detached from the frame. Specifically, the blind assembly includes a catch that snaps into a slot on the header. This feature reduces inventory, because assemblies can be made to order by snapping any one of a plurality of blinds (e.g. having a desired feature such as color) into a common frame. This feature also facilitates subsequent changes to the assembly, such as replacing a blind having one feature with a blind have a different feature.  
           [0011]    In a fifth aspect of the invention, the blind actuator rod includes an improved technique for securing the actuator cords. More specifically, small barrels are mounted transversely in the rod; and the actuator cords are secured within the barrels. This technique eliminates the prior art need to glue the cords to the barrel, with the attendant manufacturing difficulties and costs.  
           [0012]    These and other objects, advantages, and features of the invention will be more readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a front elevational view of a door incorporating the blind assembly of the present invention;  
         [0014]    [0014]FIG. 2 is a front elevational view of the blind assembly;  
         [0015]    [0015]FIG. 3 is a rear perspective view of the assembly;  
         [0016]    [0016]FIG. 4 is an exploded fragmentary view of the assembly;  
         [0017]    [0017]FIG. 5 is a top cross-sectional view of the assembly showing the blinds retained in the frame taken along the line V-V in FIG. 3;  
         [0018]    [0018]FIG. 6 is a rear elevational of the interior of the header of the blind assembly;  
         [0019]    [0019]FIG. 7 is a side cross-sectional view of the height control mechanism taken along line VII-VII in FIG. 3;  
         [0020]    [0020]FIG. 8 is a fragmentary side cross-sectional view of the door of FIG. 1 taken along line VIII-VIII;  
         [0021]    [0021]FIG. 9 is a fragmentary bottom cross-sectional view of the door of FIG. 1 taken along line IX-IX; and  
         [0022]    [0022]FIG. 9A is a front elevational view of a clip of the assembly. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    A blind assembly according to a preferred embodiment of this invention is illustrated in FIGS. 1-3 and generally designated  10 .  
         [0024]    I. Structure  
         [0025]    The assembly  10  includes a window pane  12 , a frame  20 , a set of blinds  22 , a tilt control mechanism  24 , and a height control mechanism  26 . The assembly  10  is described for installation over a door D and doorlight L. However, the assembly  10  may be installed over other, various window types.  
         [0026]    The frame  20  is preferably molded of plastic, although other materials, such as wood or metal, may be used. The frame  20  includes top and bottom sides  28  and  30  and left and right sides  32  and  34 . The sides  28 ,  30 ,  32 , and  34  meet at right angles and form a rectangle, although the frame  20  may include a larger or smaller number of sides and form other shapes, such as a triangle or octagon. A pane opening  36  is defined in the center of the frame  20 . Although the frame will be described with reference to a rectangular pane opening  36 , and accordingly a rectangular window pane  12 , it is to be understood that the opening can be of essentially any shape, such as oval or triangular.  
         [0027]    As seen in FIG. 4, each of the bottom, left and right sides  30 ,  32 , and  34  of the frame  20  includes a rib  40 , extending along its length. The rib  40  is a substantially rectangular protrusion that extends approximately the length of the pane opening  36  on each side of the frame  20 . The rib  40  is preferably integrally molded as part of the frame  20 , however the rib  40  may be separately formed and attached to the frame  20  by conventional means.  
         [0028]    Connected to each rib  40  is a blind guide  42 . Blind guides  42  are preferably molded of plastic, but may be produced of other materials such as metal or plastic. As will be explained below, the blind guides  42  guide the blinds  22  during use and secure the pane  12  to the frame  20 . Further, the blind guides  42  reinforce the frame  20  and prevent viewing of the internal workings of the assembly  10  when the assembly is installed. Each blind guide  42  has a connecting portion  44  and a blind retainer  46 .  
         [0029]    The connecting portion  44  is a substantially U-shaped section of each blind guide  42  that defines a cavity, the cavity fitting over a rib  40  of the frame  20 . As shown in FIG. 5, the dimensions of the connecting portion  44  are preferably such that there is a close fit between each connecting portion  44  and the corresponding rib  40 . When connected to the rib  40 , a first leg  48  of the connecting portion  44  is in contact with the pane  12  and a second leg  50  of the connecting portion  44  is in contact with the frame  20 . This construction secures the pane  12  to the frame  10 . The connecting portion  44  can be connected to the rib  40  by any conventional means, such as the use of glue or fasteners.  
         [0030]    Further, each blind guide  42  includes a blind retainer  46 . The blind retainer is an essentially C-shaped section of the blind guide  42  and is connected to the connecting portion  44 . The width  52  of the blind retainer  46  is approximately equal to the width  54  of the blinds  22 . When connected, the open side of the blind retainer  46  faces the pane  12  of the assembly  10 , providing a channel for the blinds  22  to travel in as they are raised and lowered during use. As with the connecting portion  44 , the blind guide has one leg  56  that contacts the pane  12  of the assembly  10 .  
         [0031]    The connecting portion  44  and blind retainer  46  are preferably molded as an integral piece, though the elements can be formed separately and later connected. If molded as an integral piece, the back leg  58  of the blind retainer  46  and the first leg  48  of the connecting portion  44  are preferably molded as a single leg, thus connecting the two sections. If not molded as an integral piece, the back leg  58  of the blind retainer  46  is preferably connected to the first leg  48  of the connecting portion  44  by conventional means, such as the use of glue or other adhesive.  
         [0032]    The set of blinds  22  are conventional window blinds and, therefore, will not be described in detail. The blinds include a plurality of slats  64 , preferably manufactured of vinyl or aluminum; of course, other materials such as wood may be used. As discussed above, the blinds  22 , and specifically the ends  66  and  68  of the slats  64  of the blinds  22 , are loosely retained in the blind retainers  46  of the left and right sides  32  and  34  of the frame  20 . A header  70 , as seen in FIG. 4, from which the slats  64  are suspended, is fixedly mounted on the top side  28  of the frame  20 . The slats  64  are suspended from conventional lift adjustment and tilt adjustment, or string ladder, tilt cords  74 . The lift cords  72  have first and second ends  75  and  76 ; the first ends  75  are threaded through apertures (not shown) defined by the slats  64  and secured to the lowermost slat  77 . The second end  76  of each lift cord  72  is secured within the header  70 . Front and rear tilt cords  78  and  79  extend along the front and rear edges  80  and  82  of the slats  64 . A connector cord (not shown) extends between the front and rear tilt cords  74  and supports each slat  64 . The tops of the tilt cords  74  are secured within the header  70 .  
         [0033]    The header  70  is a substantially L-shaped bar that is connected to the top side  28  of the frame such that a ledge is formed along the top edge of the pane  12 . The header  70  can be connected to the frame  20  by any conventional means, such as integrally molding the header  70  as part of the frame  20  or connecting the two using an adhesive. The header  70  includes an attachment leg  106 . The attachment leg  106  is a short protrusion extending at a right angle from the back leg  108  of the header  70  such that the back leg  108  of the header  70  lies flat against the pane  12  and the attachment leg is connected to the interior of the frame  20 . The header  70  further includes a base leg  110  having slots  112  for the connection of the tilt control mechanism  24  and height control mechanism  26  to the frame  20 . Each slot  112  is a substantially rectangular groove in the base leg  110  of the header  70 .  
         [0034]    As seen in FIGS. 4 and 5, the tilt control mechanism  24  includes a tilt actuator  84 , which is slidably mounted along the left side  32  of the frame  20 . The tilt actuator  84  includes a spine  86  that protrudes from the tilt actuator  84  and fits within a groove  85  present along the left side  32  of the frame. The spine  86  is preferably a substantially rectangular protrusion and the groove  85  is preferably substantially U-shaped, the height of the spine  86  being approximately equal to the depth of the groove  85 . Additionally, the tilt actuator  84  includes a rearward extending connector  88  for connecting to the remainder of the tilt control mechanism  24 , as will be explained in more detail below. The connector  88  extends inwardly from this the groove  85  into the interior of the frame  20 . Preferably, a portion of the edge of the frame is cut away along the groove  85  to facilitate movement of the tilt actuator  84 , the tilt actuator  84  being positioned along this cut-away portion  87 .  
         [0035]    The remainder of the tilt control mechanism  24  is located within the interior of the frame  20  and is not visible to the user. The tilt control mechanism  24  further includes a tilt belt  90  attached to the tilt actuator  84  by the connector  88 . The tilt belt  90  wraps around a tilt gear  92  that is affixed to a tilt bar  94 , preferably with screws or adhesive. The tilt belt  90  preferably includes grips  98  that interfit with teeth  100  on the gear to provide a more secure grip between the two. A tilt control gear  93  is essentially identical to the tilt gear  92  and is mounted at the bottom of the frame  20 . The tilt gear  92  and tilt control gear  93  control rotation of the tilt belt  90  during operation of the assembly  10 . The tilt belt  90  is most preferably molded from plastic, although other suitable materials such as rubber and fabric may be used. A portion of the tilt belt  90  optionally consists of a spring  102 , the spring  102  accounting for thermal expansion of the resulting belt. The tilt bar  94  extends lengthwise within the interior of the header  70  and is supported within barrel  114  which snaps into the floor of the header  70 . The front and rear tilt adjustment cords  78  and  79  are secured to the tilt bar  94 .  
         [0036]    The tilt gear  92  and tilt control gear  93  are housed within baskets  104 . Each basket  104  includes two side walls  106  and a back wall  108 . Each side wall includes a nesting portion  110 , which is a substantially semicircular ridge along the top edge of the wall. The tilt gear  92  and tilt control gear  93  rest on the nesting portions  110  of the side walls  106 . The back wall  108  connects the basket  104  and is attached to the frame  20 . The back wall  108  can be connected to the frame  20  by any conventional means, such as screwing the back wall  108  onto the frame  20  or attaching the two with an adhesive.  
         [0037]    The height control mechanism, or adjuster,  26  includes a height actuator  120  which is slidably mounted on the right side  34  of the frame  20 . The height actuator  120  is essentially identical to the tilt actuator  84  and includes a spine  122  which interfits with a groove  124  on the right side  34  of the frame  20 . As with the tilt control mechanism  24 , the groove  124  preferably includes a cut-away portion to facilitate movement of the height actuator  120 , and thus adjustment of the blinds  22 . The height actuator  120  further includes a connector  126  that connects the height actuator  120  to the height control mechanism  26 .  
         [0038]    The connector  126  of the height actuator  120  is attached to a height belt  128  which is wrapped around an adjustment gear  130  and adjustment control gear  131 , which are housed in baskets  104 . The height belt  128 , adjustment gear  130  and adjustment control gear  131  are essentially identical to the tilt belt  90 , tilt gear  92  and tilt control gear  93 , and therefore will not be described in further detail. The height control mechanism  26  further includes an adjustment rod  136 , a threaded rod  138 , and a rod support  140 . The adjustment rod  136  is a substantially circular rod that is connected to the adjustment gear  130  such that when the adjustment gear  130  rotates, the adjustment rod  136  rotates. Optionally, a bar can be used to connect the adjustment gear  130  to the adjustment rod  136 . The adjustment rod  136 , or at least a substantial portion thereof, is hollow and is internally threaded. The adjustment rod includes throughholes  137  through which the second ends  76  of the lift cords  72  are threaded. The first ends of the lift cords  72  are preferably knotted to secure them to the adjustment rod  136 . A cap  139  is also connected to the second end  76  of each lift cord  72  around the knotted portion to further ensure the connection of the lift cords  72  to the adjustment rod  136 .  
         [0039]    The threaded rod  138  is a substantially circular rod having threads along substantially its entire the length, the threads of the threaded rod  138  corresponding to the threads of the adjustment rod  136  so that that threaded rod  138  can be screwed into the adjustment rod  136 . One end of the threaded rod  138  is screwed at least partially into the adjustment rod  136  and the opposite end of the threaded rod  138  being rigidly connected to the rod support  140 , such that as the adjustment rod  136  rotates the adjustment rod  136  is screwed onto the threaded rod  138 . The rod support  140  preferably includes a circular portion  142  that houses an end of the threaded rod  138  and prevents the threaded rod  138  from rotating during operation of the assembly  10 . The rod support  140  also preferably includes a clamp  144  that is connected to the header. The clamp  144  is preferably substantially U-shaped and interfits with the base leg  110  of the header  70  to connect the rod support  140  to the header  70 , and thus the frame  20 . Alternatively, the rod support may be connected to the header  70  by other conventional means, such as the use of glue or fasteners.  
         [0040]    Each of the adjustment rod  136  and tilt bar  94  extends through barrels  114 , thus connecting the tilt control mechanism  24  and height control mechanism  26  to the barrels  114 . Barrels  114  include catches  116  that interlock with the slots  112 . Each barrel  114  is essentially two figure-8 shaped sections, each section having a large circle  118  beneath a small circle  120 . A base  122  is attached to the bottom of each large circle  118  and extends between the two sections to connect them. A catch  116  is a substantially T-shaped protrusion that extends from the bottom of each base  122 . Each catch  116  is designed to “snap” fit with a slot  112  on the header  70  to connect the tilt control mechanism  24  and height control mechanism  26  to the header  70 .  
         [0041]    As can perhaps be best seen in FIG. 8, latches  150  are connected along the top side  28  of the frame  20 . Each latch  150  includes a short frame leg  152  connected to the top side  28  of the frame  20  and a door leg  154  that is substantially longer than the frame leg  152  and extends in a direction opposite that of the frame leg  152 . An intermediate leg  156  connects the frame leg  152  and door leg  154  and is preferably perpendicular to them both. There are preferably at least two latches  150  connected along the top side  28  of the frame  20 . Latches  150  can be formed from any materials, but are preferably metal, and can be connected to frame  20  in any conventional manner.  
         [0042]    As can be seen in FIG. 9, clips  160  are connected along either the bottom side  30  or a lower portion of both the left and right sides  32 ,  34  of the frame  20 . Each clip  160  is substantially L-shaped and includes a base leg  164  and an extending leg  166 . Each clip  160  optionally includes a substantially rectangular lip  162  extending perpendicularly from the base leg  164  of the clip  160 . The clips  160  are rotatably connected to the frame  20  such that, if the lip  162  is pulled, the clip  160  rotates. The clips can be connected to the frame by any conventional means, but are preferably connected to the frame  20  with screws.  
         [0043]    II. Operation  
         [0044]    The assembly  10  is preferably installed over the doorlight of an existing door. However, the assembly  10  may be used in conjunction with any window style or with windows in any type of structure, such as a home or office building.  
         [0045]    Before installing the assembly, the blinds  22  must be installed. To install the blinds  22 , the catches  116  of the barrels  114  connected to the tilt control mechanism  24  and the height control mechanism  26 , which in turn are connected to the blinds  22 , are snapped into slots  112  on the header  70 . To change the color of the blinds, the barrels  114  can be detached from the header  70  and new barrels  114 , with new blinds  22 , can be snapped in.  
         [0046]    After installing the blinds, the assembly  10  is positioned so that the blinds  22  are sandwiched between the pane  12  and the existing doorlight. To install the assembly  10  on a doorlight, the latches  150  of the assembly  10  are first placed over the existing frame of a doorlight in such a manner as to allow the door leg  154  of each latch  150  to “snap” in between the frame of the existing doorlight and the door. The snapping interaction of the latches  150  and the existing frame provides a secure connection of the assembly to the door.  
         [0047]    After connecting the assembly  10  to the door, the clips  160  are rotated such that the extending leg  166  of each clip  160  “snaps” between the frame of the existing doorlight and the door. In this case, the securing of the clips  160  between the doorlight frame and door prevents the assembly  10  from swinging or swaying as the door is opened or closed or during windy conditions.  
         [0048]    To raise or lower the blinds  22 , the user grasps the height actuator  120  of the height control mechanism  26  and slides height actuator  120  vertically along the cut away portion  132  of the groove  124 . As the user slides the height actuator  120  down, the height belt  128  is moved downward, thus rotating the adjustment gear  130  and, in turn, the adjustment rod  136 . As the adjustment rod  136  rotates, it is threaded onto the threaded rod  138  and the lift cords  72  are coiled onto the adjustment rod  136 , thus pulling the slats  64  vertically upward. The slats  64  may be raised to any height desired by the user. When the slats  64  are raised to the desired position, the user ceases sliding the height actuator  120  down the track  40 .  
         [0049]    To lower the blinds  22 , the user slides the height actuator  120  vertically upward along the groove  124 . As the height belt  128  is pulled upward, the adjustment gear  130  is rotated in the opposite direction, causing the lift cords  72  to unwind from the adjustment rod  136  and lower the slats  54 .  
         [0050]    To open the blinds  22 , the user grasps the tilt actuator  84  and slides it along the groove  85  along the left side  32  of the frame  20  to the middle of the left side  32 . As the tilt actuator  84  is moved, the tilt belt  90  is moved causing the tilt gear  92  to rotate. As the tilt gear  92  rotates, the tilt cords  74  are twisted causing the slats  64  to rotate. When the tilt actuator  84  is positioned in the middle of the assembly  10 , the front and rear tilt cords  74  are level, and the connector cords are horizontal. Thus, the slats  64  lie in a horizontal position, and the blinds  22  are opened. To close the blinds  22 , the user slides the tilt actuator  84  to upwards or downwards from the middle position. This causes the tilt gear  92  to rotate, thus rotating the tilt bar  94  and causing the tilt cords  74  to twist. As the tilt cords  74  twist, one edge of the slats  64  is pulled upward causing the blinds to close.  
         [0051]    The above description is that of a preferred embodiment of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.

Summary:
A retrofit blind assembly for a doorlight. The assembly includes a frame, a transparent panel, and a blind snap-fitted to the frame. The blind actuator includes gears and a toothed belt for positive, non-slip actuation. A pair of blind guides are mounted on the opposite sides of the frame to receive and guide the opposite ends of the blind. The mounting system includes a pair of brackets that can be secured between the doorlight and the door and upon which the assembly can be hung. The mounting system also includes a pair of movable catches on the lower portion of the frame snap that can be locked behind the doorlight to secure the lower end of the assembly.