Abstract:
An actuator structure for concurrently unlatching a pair of sash tilt latches. The actuator structure includes a housing mounted to a sash which slides within a window frame, a winder rotatably connected to the housing and extending into an interior of the sash, the winder having a diametral slot therein. The actuator structure further includes a filament slidingly received within the slot with ends of the filament connected to the latches. As the winder is rotated in a first direction, the filament coils around the winder to draw the latches inwardly, thereby releasing the sash from the frame.

Description:
RELATED APPLICATION  
       [0001]    This application is a continuation under 37 C.F.R. 1.53(b) of U.S. application Ser. No. 09/450,648 filed Nov. 23, 1999, which application is incorporated herein by reference. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The present invention deals broadly with the field of windows, and more particularly with those windows, such as double-hung windows, wherein a sash slides within a frame. The invention specifically relates to mechanisms for retaining a window sash within a frame at an intended location along an axis perpendicular to a plane defined by the window frame within which the sash slides, and more particularly to an actuator for such a sash retention mechanism.  
         BACKGROUND  
         [0003]    The prior art includes many types of windows which are employed to bring light into a building. One popular type of window known in the prior art is a double-hung window, and the background of the present invention will be described in that context (although it should be noted that the present invention can certainly be used with any tiltably removable sliding sash window and is not limited to double-hung windows).  
           [0004]    A double-hung window typically employs two movable sash assemblies, each carrying its own pane of glass, which are typically movable vertically within the frame. For most double-hung windows it is highly desirable that the sashes be inwardly tiltable and/or removable, so that the glass portions of the sash assemblies can be easily cleaned. Various types of sash retention mechanisms have been utilized to effect maintenance of a sash in the desired position yet allow it to be tilted inwardly or removed for cleaning. The present invention is directed to a sash retention mechanism actuator, so the remainder to this background discussion will focus on such mechanisms.  
           [0005]    One type of sash retention mechanism utilizes a pair of independently-operable latch elements carried by the sash. The latch elements extend laterally out of the sash and into a groove or track formed by the frame. One latch element extends laterally from one side of the sash, and a second latch element extends laterally from the other side of the sash. When it is desired to remove a sash, the person removing the sash releases (i.e., retracts the latch element back into the sash) one latch with one hand and releases the other latch with the other hand. The sash is then tilted or slid out of its normal position and removed from the frame for cleaning. Such an “independent-latch” sash retention mechanism has a number of drawbacks, not the least of which is that the person removing the window sash needs full availability of both hands to effect release cf the latches.  
           [0006]    To address problems associated with “independent-latch” sash retention mechanisms, attempts have been made to design a mechanism for concurrently releasing both latches (that is, for simultaneously effecting retraction of the latches). One such “concurrent-latch” sash retention mechanism is disclosed in commonly-assigned U.S. patent application Ser. No. 09/328,085. Latch elements (i.e., the elements that extend into the groove or track in the window frame) for “concurrent-latch” mechanisms can move in and cut relative to the sash along a straight line or they can pivot in some fashion (as disclosed in the aforementioned commonly-assigned patent application), but regardless of the specific type of latch element being used, an actuator of some sort is necessary to draw the latch element out of the corresponding groove or track in the window frame so that the sash can be removed or tilted as necessary. The present invention relates in particular to an improved actuator for a “concurrent-latch” sash retention mechanism.  
           [0007]    While “concurrent-latch” sash retention mechanisms are theoretically superior to “independent-latch” mechanisms due to the one-hand versus two-hand operation advantage discussed above, the actuators in prior art “concurrent-latch” mechanisms have been problematical. For example, one design, shown somewhat pictorially in FIGS.  1 - 4  hereof, uses a plastic strap captured by a winder to actuate a pair of linear latch elements (not shown).  
           [0008]    In the “plastic-strap/linear-latch” design discussed immediately above and partially shown pictorially in FIGS.  1 - 4  hereof, the tilt actuator includes a tilt lever (not shown) mounted at the top of the sash (assuming for the purposes of this discussion that the double-hung window is in its typical, vertical orientation with the sashes sliding up and down rather than side to side). The tilt lever is connected to the upper end of a cylindrical winder which rotates about a vertical axis. The lower end of the winder fits into a round aperture formed by a housing contained within the sash frame.  
           [0009]    In addition to the winder aperture, the housing also forms a pair of laterally extending channels that extend from the winder aperture to the outer lateral edges of the housing. The lower end of the winder, the end that rotates within the winder aperture, is slotted in a manner that would appear to be a screwdriver slot as viewed from the bottom. This slot is a simple, vertical-walled slot extending diametrally through the lower end of the cylindrical winder.  
           [0010]    A plastic strap, of the type used to bind or bundle various materials, having a generally rectangular cross section, is received within the “screwdriver slot” in the lower end of the winder. Note that FIGS.  2 - 4  show only the edge of the strap, not its width. When the tilt lever is in its un-activated position the winder slot is aligned with the channels in the housing, as shown in FIG. 2. As the tilt lever is rotated, as shown in FIG. 3, the winder is supposed to evenly and equally act on the strap to simultaneously draw the linear latch elements inwardly and out of their corresponding grooves or tracks in the window frame, to permit tilting/removal of the sash.  
           [0011]    While the strap-type actuator mechanism shown in FIGS.  1 - 4  is an advance over typical “independent-latch” mechanisms that require two-hand operation, it has certain limitations. One of its limitations is that it employs a housing, and another has to do with its use of a strap.  
           [0012]    As noted above, one shortcoming of prior art strap-type sash retention mechanism actuators is that they include a “housing,” defined herein as a component that receives the lower end of a winder and forms channels for laterally guiding the strap. An actuator housing such as that employed by prior art strap-type actuators is an unnecessary part (as compared to preferred embodiments of the present invention) that adds cost in and of itself, increases the assembly time and cost, and introduces an additional source of friction and binding for the strap, thus potentially making it more difficult to actuate the tilt mechanism.  
           [0013]    While the housing of the prior art strap-type actuator design may cause certain problems, FIG. 4 shows what would happen if the housing in this particular design were omitted. Initially, when the tilt lever is in its normal, unactivated position, the slot in the lower end of the winder is aligned with the linear latch elements. See FIG. 2. If the housing were absent, movement of the tilt lever would cause the linear latches to move inwardly only minimally for a given incremental rotation of the winder. Most of this initial movement would be taken up with simply changing the orientation of the strap from straight (FIG. 2) to angled or tangential (FIG. 4). That is, initial movement of the tilt lever would tend to cause the strap to “take a tangential shortcut” and not result in linear movement of the strap in the sense of X degrees of rotation of the winder consistently resulting in Y inches of movement of the strap. Rather, the translation of winder rotation to latch movement would be quite non-linear, and this could be misleading or feel strange to the operator, who might only operate the tilt latch on rare occasion. The rationale for the housing, given the initial, unactivated orientation of the strap slot, can now be understood.  
           [0014]    Another shortcoming of this type of actuator mechanism is that the housing can introduce additional friction on the strap, and this can result in binding of the mechanism and possibly strap breakage, over time.  
           [0015]    Still another shortcoming of the strap type of “concurrent-latch” actuator discussed above is the strap itself, given that it can become twisted and bind at various locations within the sash, irrespective of whether a “housing” is employed.  
           [0016]    It is to these dictates and shortcomings of the prior art that the present invention is directed. It is an actuator for a “concurrent-latch” sash retention mechanism which addresses these dictates and problems and provides solutions which make the invention a significant advance over prior art sash retention mechanism actuators of the “concurrent-latch” variety.  
         SUMMARY  
         [0017]    The present invention is an actuator device for unlatching a sash tilt latch which is intended to maintain a window sash, such as in a double-hung window, in an intended path of reciprocation during opening and closing of the window. At the same time, however, the latch can be retracted to release the sash from its position in the defined path and allow it to be tilted for cleaning or removal. In a preferred embodiment, a pair of latches which extend oppositely in lateral directions are actuated by the structure. The actuator includes a housing which is mounted to the sash. A winder is rotatably connected to the housing and extends into an interior cavity within the sash. The winder has a longitudinal axis and forms a diametral slot. A flexible cord having a substantially round cross-section is slidably received within the winder slot. Ends of the cord are connected to the latches. As the winder is rotated in a particular direction, the cord coils around the winder to draw the latches inwardly. The sash is, thereby, released from the frame.  
           [0018]    In a preferred embodiment of the invention, the winder includes a slit at its lower end, the slit extending through an imaginary vertical axis about which the winder rotates.  
           [0019]    The flexible cord is received within the slit, and, in a preferred embodiment, the cord has a larger diameter than does at least a portion of the slit. A bulge in the slit above its narrowest portion does, however, have a diameter greater than that of the cord. Consequently, prongs defined on opposite sides of the slit can be urged apart to admit the cord into the bulge. With the cord received in the bulge, because of the bulge&#39;s greater diameter than that of the cord, the cord will be free to move through the bulge portion of the slit and will effectively equalize pressure applied to the oppositely facing tilt latches.  
           [0020]    The present invention is thus improved apparatus to be employed in mounting and maintaining a sash within a window frame. More specific features and advantages obtained in view of those features will become apparent with reference to the accompanying drawing figures, the DETAILED DESCRIPTION OF THE INVENTION, and appended claims.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 is a perspective pictorial view of a strap-type prior art sash retention mechanism actuator;  
         [0022]    [0022]FIG. 2 is a bottom plan pictorial view of the prior art strap-type actuator of FIG. 1, with the winder in its unactivated position;  
         [0023]    [0023]FIG. 3 is a bottom plan pictorial view of the prior art strap-type actuator of FIG. 1, with the winder in its activated position;  
         [0024]    [0024]FIG. 4 is a bottom plan pictorial view of the prior art strap-type actuator of FIG. 1, with the housing removed and the winder in its activated position;  
         [0025]    [0025]FIG. 5 is a perspective, exploded view of one type of latch assembly suitable for use with an actuator according to the present invention, including a pivoting “blade” and its supporting and related apparatus and structure, with the window sashes and actuator cord being shown in phantom, and some portions of the structure being broken away;  
         [0026]    [0026]FIG. 6 is a front elevational view of the latch assembly of FIG. 5, as mounted within a window sash, showing the latch element in various positions;  
         [0027]    [0027]FIG. 7 is an exploded perspective view of a combined window-lock/tilt-latch actuator assembly according to the present invention;  
         [0028]    [0028]FIG. 8 is a top plan view of the combined windowlock/tilt-latch assembly of FIG. 7, with the sweep and tilt latch lever in their locked positions;  
         [0029]    [0029]FIG. 9 is a top plan view of the combined windowlock/tilt-latch assembly of FIG. 7, with the tilt latch handle in its unlocked/activated position, and the sweep in its unlocked/activated position in phantom line;  
         [0030]    [0030]FIG. 10 is a front elevational view of the assembly of FIG. 7, with the sweep and tilt latch handle in their locked/unactivated positions;  
         [0031]    [0031]FIG. 11 is a bottom plan view of the assembly of FIG. 7;  
         [0032]    [0032]FIG. 12 is an enlarged side elevational view of the cord-retaining end of a second embodiment of a winder according to the present invention, with the winder in its activated/unlocked position and the cord (in phantom) wrapped around the winder;  
         [0033]    [0033]FIG. 13 is an enlarged view of the lower end of the winder of FIG. 12, again showing the cord in phantom but with the winder in its unactivated/locked position and with the cord not wrapped around the winder; and  
         [0034]    [0034]FIG. 14 is a front elevational pictorial view of the actuator of the present invention in conjunction with a pair of latch assemblies mounted in a double-hung window. 
     
    
     DETAILED DESCRIPTION  
       [0035]    The present invention, as discussed above, is directed to a “concurrent-latch” actuator for a sash retention mechanism.  
         [0036]    Referring now to the drawings, wherein like reference numerals denote like elements throughout the several views, FIG. 5 is an exploded view illustrating dual sashes  20 ,  22  of a double hung window and a pivoting blade  24 , which is intended to be recessed within a cavity  26  in the inner sash  20 . The cavity  26  in the sash  20  is overlain, on a side of the sash, by a face plate  28  mounted generally flush with the outwardly facing side surface  30  of the sash  20 . The face plate  28  is part of an end plate assembly  32 .  
         [0037]    The figures illustrate a blade member  24  which is pivotally mounted for rotation about an axis generally transverse to a plane defined by the window sash  20 . It should be noted, however, that the actuator of the present invention, discussed below, could be used with other types of latch elements, including without limitation linearly acting latch elements as opposed to pivoting blade(s)  24 .  
         [0038]    [0038]FIG. 5 illustrates a coil spring  38  which is shown as being connectable, at one end thereof, to a hook member  40  of the blade  24 . The other end of the coil spring  38  is connectable to the base  36  of the end plate assembly  32 . The coil spring  38 , thereby, biases the blade  24  for rotation, in a direction as seen in FIG. 5, in a clockwise direction.  
         [0039]    A yoke member  42  is attached to the blade  24  to effect selective overcoming of the bias of the coil spring  38  in order to retract the blade  24  for a purpose discussed hereinafter. The yoke member  42  is illustrated as being constructed of a wire stock formed into a bail, opposite ends of which are passed through an aperture  44  provided in the blade  24 . The bail  42  thereby has an end, proximate the blade  24 , which serves to apply force to the blade  24  in a direction, as viewed in FIG. 5, counter clockwise so as to overcome the bias of the coil spring  38 . The wire from which the bail  42  is formed is provided with a narrow neck  46  at an end remote from blade  24 . The neck  46  defines a channel  48  which extends away from the blade  24 , when the bail  42  is connected to the blade  24 , to facilitate connection of an actuator mechanism. A remote end of the actuator is illustrated in FIG. 5. A segment of flexible filament or cord  50  is shown as extending through the narrowed channel  48  formed in the neck  46 , an end of the filament  50  having a sleeve  52  crimped onto the filament  50 . Typically, the sleeve  52  would have a diameter smaller than an expanded channel  54  formed within the bail  42  so that the filament  50  end, with the sleeve  52  crimped thereon, could be slid through the expanded channel  54  and then withdrawn into the narrowed channel  48  which would have a width smaller than the diameter of the sleeve  52 . The remainder of the actuator structure (i.e., the parts in addition to the filament or cord  50 ) is discussed in detail below.  
         [0040]    [0040]FIG. 5 also illustrates a portion of a balance tube  56  which defines an elongated trough or track  58  into which blade  24  extends when in its non-fully-retracted position(s).  
         [0041]    [0041]FIG. 5 illustrates a slot  64  formed in the balance tube  56  at the bottom of the trough  58 . This slot  64  is formed at a location such that, when the window sash mechanisms are in their closed positions, a corresponding slot  66  in the end plate assembly face plate  28 , through which the blade member  24  can extend, is registered with the slot  64  formed in the balance tube trough  58 .  
         [0042]    [0042]FIG. 6 illustrates the blade  24  mounted to end plate assembly  32 . That figure shows a second position of the blade  24  in solid line and first and third positions of the blade  24  in phantom line.  
         [0043]    The first position of the blade  24  is such that the blade  24  is fully retracted within sash cavity  26 . The third position of the blade  24  is one wherein the blade  24  not only extends into the trough  58  engaging the bottom thereof, as it does in its second position, but wherein the blade  24  extends fully to the bottom of the trough  58  and into and through the slot  64  formed in the bottom of the trough  58 .  
         [0044]    When the blade member  24  is in its second position, it will ride in the trough  58  and facilitate raising and lowering of the window sash  20 . It serves as a track rider which rides on the track defined by trough  58 , and the thickness of the blade member  24  can be made so that there is a minimum, if any, wobble of the sash  20  relative to the window frame  62  of which balance tube  56  is a part. Because of the biasing of the blade  24  to the second position by the coil spring  38 , the blade  24  will tend to remain received within the trough  58  as long as action is not taken to operate the actuator in order to overcome the bias of the spring  38  and cause rotation of the blade  24  to its first position.  
         [0045]    The bias of the spring  38  is sufficiently strong such that, when the sash  20  is moved to its closed position with the slots in the face plate  66  and bottom of the trough  64  registered, the blade  24  will extend into the slot in the trough  64 . This will effect an even more positive preclusion of movement of the sash  20  in a direction perpendicular to a plane defined by the window frame  62 . The sash  20  will, thereby, be even more securely disposed to deter unwanted removal.  
         [0046]    As will be able to be seen then, unless some positive action is taken to move the blade  24  in a rotational manner to its first position, the blade  24  will be maintained in either its second or third positions. When it is desired, however, to remove or tilt the sash  20 , operation of the actuator means (described in detail below) can be initiated to overcome the bias of the coil spring  38  and rotate the blade  24  to its first position. With the blade  24  in this position, there will be no obstruction to rotation of the sash  20  out of its location between the frame  62  or, if desired, removal of the sash  20 .  
         [0047]    An exemplary latch mechanism having been described, attention can now turn to the actuator structure that effects retraction of the latches. With reference to the exemplary latch elements disclosed above, the actuator structure permits volitional rotation of the blade  24  in the counter clockwise direction, as viewed in FIG. 5; and the other blade  24  (shown on the right side of FIG. 14) in the clockwise direction. The actuator structure includes means for inwardly drawing both ends of the filament  50  which in turn inwardly draw the yokes  42  to effect counter clockwise rotation of the left blade  24  and clockwise rotation of the right blade  24 . Of course, other types of latch elements (e.g., linear latch elements) could be used. The details of a preferred actuator are set forth below.  
         [0048]    With reference to FIGS.  7 - 11 , a preferred embodiment of the tilt latch actuator of the present invention can now be described. As shown, the preferred actuator is actually employed in combination with an integrated lock/tilt latch assembly  70  for a double-hung window. And it will be assumed for the purpose of describing the preferred embodiment that the window is oriented in the typical fashion such that the sashes move up and down rather than side to side. But those skilled in the art will recognize that the present invention is not limited to double-hung windows or for that matter double-hung windows that are oriented in the typical up-and-down fashion.  
         [0049]    Integrated lock/tilt latch assembly  70  includes, starting at the top of FIG. 7, a traditional rotatable sweep  72  (carried by the lower sash  20 ) that works in conjunction with a keeper (not shown) attached to the upper sash  22  to lock the lower sash  20  to the upper sash  22  when the sashes are in their fully closed positions and the sweep  72  is in its locked position, as shown in solid line in FIG. 9. Sweep  72  is rotatably supported by a housing  74  in conventional fashion, housing  74  having a generally smooth top surface for supporting the underside of the sweep  72 , and a variety of bosses, studs, etc. extending downwardly from its underside for accepting and supporting the various components of the integrated lock/tilt latch  70 .  
         [0050]    Further with reference to FIG. 7, housing  74  provides a round aperture in its upper surface for receiving the sweep  72 . This aperture is located in the middle of the housing, side-to-side, and toward the front of the housing front-to-rear, with the front of the housing normally being mounted adjacent the inside of the room. Depending from the lower surface of the sweep  72  is a generally cylindrical stud  76  that is round at its upper end; has a pair of opposed flats  78  in its middle section; and a reduced diameter round tip  80  at its lower end. After the stud  76  is inserted into the sweep aperture in the housing, a washer-like retainer  82  is fixed to the lower tip  80  of the stud  76 , the retainer  82  serving to hold the sweep  72  against the housing  74 .  
         [0051]    A leaf spring  84  is mounted within the housing  74  in such a way as to resiliently act on the flats  78  in the middle section of the sweep stud  76 , so as to tend to maintain the sweep  72  in either its fully unlocked or open position (as shown in phantom line in FIG. 9) or its fully locked or closed position (as shown in solid line in FIG. 9). That is, leaf spring  84  acts against one flat  78  or the other, depending on whether the sweep  72  is fully closed or fully open, to tend to keep the sweep  72  in that position. If the user wishes to rotate the sweep  72  from one position to the other, he or she must overcome the relatively small spring force created by the spring  84 .  
         [0052]    Still referring to FIG. 7, the underside of the housing  74  also supports a tilt lever  66 . The top surface of the tilt lever  86  can carry a short upwardly extending stud (not shown) that can fit within a boss  88  depending from the housing  74 . Tilt lever  86  can rotate relative to housing  74 , and in fact includes a handle portion  90  that is accessible through a cutout  92  in the rear edge of the housing. Handle portion  90  can include a raised lip  94  on its upper surface, so that the operator can easily get a finger or tool into the cutout  92  and push against the raised lip  94  to initiate the rotation of the tilt lever  86 . Once handle portion  90  has “escaped” cutout  92 , the operator can gain additional purchase by grasping progressively longer portions of handle  90 . As shown in FIG. 9, tilt handle  90  is rotated counter clockwise to actuate the tilt latches  24 .  
         [0053]    Extending downwardly from the tilt lever is a thin rectangular element  96  that resembles the operating tip of a standard slotted screwdriver.  
         [0054]    Tilt lever  86  and the other components mounted to the underside of housing  74  are vertically held in place by a base plate  98  that is fastened to the housing  74  in conventional fashion (e.g., threaded fasteners, staking, rivets). Base plate  98 , in plan view, has the same overall shape as housing  74 , except that base plate  98  does not have a cutout similar to cutout  92  for access to the handle portion  90  of the tilt lever  86 . Base plate  98  is smooth and flat on its bottom surface, to accommodate mounting to sash  20 .  
         [0055]    Extending downwardly from the baseplate  98 , and mounted for rotation relative thereto, is a cylindrical tube-like winder  100 . That is, winder  100  is supported at its upper end by baseplate  98 , and there is no “housing” at the lower end of the winder  100  as in the case of certain prior art actuator mechanisms. Reference is again made to FIG. 1, which shows a prior art winder mechanism having a housing at the lower end of the mechanism to support the winder cylinder. The longitudinal axis of winder  100  about which it rotates, is oriented vertically when the assembly  70  is mounted in typical fashion.  
         [0056]    At the lower end of winder  100  is a slit  102  extending through an imaginary vertical axis about which winder  100  rotates. (Slit  102  is typically “vertical” in this description only because it is assumed for the sake of convenience that the double-hung window is oriented in a conventional, vertical manner, with the sashes moving up and down.)  
         [0057]    Slit  102  is preferably widest at its very lowest point (i.e., at the lower tip of the winder), and narrows or converges as it extends upwardly, until it reaches a point up the winder where it generally attains a constant width, with one exception. At a small distance above the top of the triangular converging portion of the slit there can be a rounded “bulge”  104  in the slit, for purposes to be described below. And the slit  102  continues above the “bulge” for another small distance. This additional slit, or slit extension, above the bulge  104 , can give the structure some degree of springiness, so as to assist in accepting and retaining the cord or filament  50 , as further described below. Slit  102  splits the lower end of winder  100  into two “tines” that are resiliently biased toward one another by virtue of the natural resilience of the material fabricated into the two-tine geometry shown and described herein.  
         [0058]    Importantly, slit  102  is oriented such that it is generally perpendicular to the panes of glass in the sashes  20 ,  22  when the tilt handle  86  is in its unactivated position, e.g., as shown in FIG. 10. Tilt handle  86  is in an activated position in FIG. 9, i.e., when it is extending away from the rearward edge of the housing  74  and the handle portion  90  is no longer confined within the cutout  92  such as when it is in its unactivated state or position.  
         [0059]    With reference to FIG. 12, the top of the winder  100 ′ also forms a slit  106  for accepting the rectangular element  96  extending downwardly from the tilt lever  86 . When element  96  is engaged with slit  106 , rotation of tilt lever  86  causes winder  100  to rotate about its longitudinal (in this case vertical) axis. It should be noted that the winder  100 ′ shown in FIGS. 12 and 13 is slightly different from the winder  100  shown in FIGS.  7 - 11 , and hence is labeled  100 ′ for the sake of clarity. The main difference between winder  100  and  100 ′ is the cord slit  102  and  102 ′, respectively, as further discussed below.  
         [0060]    The cord or filament  50  can be received within slit  102 ,  102 ′, depending upon the particular embodiment involved. In either case, however, the slit  102 ,  102 ′ will have a portion, through which the cord  50  must be passed, to be received within the bulge  104 ,  104 ′. With the cord  50  received within the bulge  104 ,  104 ′, the cord will freely pass back and forth through the bulge  104 ,  104 ′ of the winder  100 . As the winder  100  is rotated, the cord  50  will be coiled about the winder  100 . Because of the relative dimensions of the cord  50  and the bulge  104 ,  104 ′, pressure brought to bear upon each tilt latch assembly  70  will be equalized.  
         [0061]    The “bulge”  104  in the winder slit  102  is located roughly at the midpoint between the lower tip of the winder  100  and the upper extent of the slit. Slit  102  is preferably less wide than the distance of the cord  50 , while the bulge  104  is preferably wider than the diameter of cord  50 . That is, the dimensions of slit  102  are slightly smaller than the diameter of cord  50  except at the bulge  104 . These relative dimensions are selected to retain cord  50  in a particular, preferred way: cord  50  has to be pushed up into the lower portion of the slit  102 , causing the “tines” of the winder  100  to separate slightly to permit the cord to be pushed up into and received within the bulge  104 . Once so located, cord  50 , since slightly smaller in diameter than the generally round bulge  104 , can slide freely therein in a lateral direction (in a lateral direction, i.e., back and forth in a direction perpendicular to the longitudinal axis of the winder). This permits the actuator to be self-balancing, so that if there is a temporary imbalance as between the force on one end of the cord  50  as compared to the other end, then the cord  50  will slide within the bulge  104  at the start of the winding process so as to balance out the difference in force on the ends of the cord  50 .  
         [0062]    This sliding of the cord  50  in the bulge  104  is very useful in terms of permitting a single actuator to actuate dual blades  24 . Such a configuration is shown in FIG. 14.  
         [0063]    It should again be emphasized that virtually any type of latch element could be used with the actuators of the present invention. The present invention is not limited to pivoting blades such as described herein.  
         [0064]    Also, the actuator of the present invention could be in the form of a separate device, and needn&#39;t be integrated into the window lock as in the preferred embodiment described herein.  
         [0065]    [0065]FIG. 13 shows an alternative type of slit  102 ′ in the winder  100 ′ This slit  102 ′ has the “bulge”  104 ′ located at the very apex of the slit  102 ′, in contrast to slit  102  shown in FIGS.  7 - 11 , wherein the bulge  104  is located approximately midway between the bottom and the top of the slit  102 . Also, slit  102 ′ is tapered all the way from its lower end to its upper end. The bulge  104 ′ is again slightly larger than the cord  50 , so that the cord can freely slide in the bulge  104 ′ to self balance the ends of the cord  50 .  
         [0066]    [0066]FIGS. 12 and 13 also illustrate small relieved areas or “scallops”  110  on the slits adjacent the bulge  104 ′, which relieve bending stress on the cord  50 , to reduce the likelihood that the cord  50  will prematurely break. The scallops  110  also help the cord to freely slide within the bulge  104 ′ during the self balancing process discussed above. It should be noted that scallops  110  could be used with winder  100  as well. The winder  100 ′ shown in FIGS. 12 and 13 is a solid circular rod as opposed to the tubular winder  100  of FIGS.  7 - 11 .  
         [0067]    [0067]FIG. 14 shows how the self balancing process works. If the cord becomes prematurely taut on the right end because there is slack on the left end, this will cause the cord to slide within the bulge  104  to balance out the actuator system. This prevents one latch  24  from completely retracting into the sash  20 , while the other latch  24  remains only partially retracted.  
         [0068]    It will be understood that this disclosure, in many respects, is only illustrative. Changes may be made in details, particularly in matters of shape, size, material, and arrangement of parts without exceeding the scope of the invention. Accordingly, the scope of the invention is as defined in the language of the appended claims.