Abstract:
The present invention relates to a night latch in particular a night latch that includes a housing, a tumbler, a button, and one resilient member. The housing, tumbler and resilient member of the present invention all serve the same function and operate in the same manner, as in our previously filed U.S. patent application filed on Mar. 27, 2006, Ser. No. 11/388,786. That is to say the housing houses the members, the tumbler prevents movement of the sliding member, and the resilient member forces the tumbler into an exposed position. In the present invention the improved button forces the tooth-like protrusion into the recess of the tumbler in a similar fashion as in our previously filed patent application. However, unique to the present invention, is a flexible bottom portion integral with the button, which biases the tooth-like protrusion of the button into the recess of the tumbler. Hence, the use of a separate biasing member is unnecessary.

Description:
[0001]     The present application is a continuation-in-part of previously filed U.S. patent application Ser. No. 11/388,786 filed on Mar. 27, 2006, as the disclosures of which are hereby incorporated by reference. The present invention relates to a night latch, in particular to a night latch that may be used in a sliding window or sliding door, which implements an improved button mechanism used for activating the night latch. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of Invention  
         [0003]     Double hung windows are a common type of window used in many homes and remodelings. There is a frame with a pair of tracks on each side of the frame. There is a top sash and a bottom sash. The top sash typically rides in the outer tracks, i.e. the tracks in the frame closest to the outside of a building. The lower sash rides in the inner track, i.e. that track that is closest to the interior of a house. The sash has a pair of vertical stiles that are joined to upper and lower horizontal stiles. One or more panes of glass are retained in the sash. There can be an inner pane and an outer pane that extends from one vertical stile to the other and from one horizontal style to the other. There can be a third pane of glass positioned similarly with a gap between the first and second panes. The gap is usually filled with an inert gas such as argon. This structure provides a window with insulating qualities. One or more muntin bars can be present to provide a look of individual lights in the window of the type that are found in older construction.  
         [0004]     In many double hung windows there is an issue of security. There is usually an outer screen that permits cooler air to ventilate into the house during the warmer months. In order to take advantage of the screen however, the bottom pane typically must be in a raised position. Double hung windows are usually provided with a sash lock that locks the lower and upper sash in position so that they cannot be opened from the outside. While this provides some security during the cooler months, the return of warm weather may make it difficult to use the sash lock in many instances. The sash lock has two positions, a locked position and an unlocked position. Thus the resident has a choice to either keep the window in a closed locked position or have the window sash unlocked and thus open to intruders.  
         [0005]     In order to provide a means of ventilating a room yet provide some security, there have been a number of night latches and vent stops that have become available in the market. One such sash stop is U.S. Pat. No. 5,248,174 owned by Ashland Products. Another type of sash stop U.S. Pat. No. 4,923,230, owned by Ro Mai. These night latches or vent stops act in a similar fashion. The night latch or vent stop is placed in the face of the upper sash. Depending on the desired amount of ventilation, the night latch can be placed at any position on the face. Once the night latch is secured in the face of the window, the tumbler can be pressed in an inward and upward fashion activating a spring mechanism that will force the tumbler to an exposed position, thus creating the impeding force required to restrict movement of the lower window sash. Other prior art vent stops are U.S. Pat. Nos. 5,553,903 and 5,806,900 both of which are owned by Ashland.  
         [0006]     As mentioned previously, the typical prior art vent stop prevented the opening of the lower sash in similar fashions. In the typical prior art the tumbler was held in a locked position via a catch portion located in the housing of the night latch. Thus, if inwardly and upwardly forces were applied perpendicularly to the face of the tumbler, these forces would free the tumbler from its locked, inactivated position, to its unlocked, activated position.  
         [0007]     While the tumblers in the prior art night latches are capable of preventing the sliding member from moving passed a certain predetermined position, these tumblers have an unfavorable characteristic. That is in the prior art vent stop, in order for the user to free the tumbler from its inactivated position to its activated position or vice versa, the user must apply a multitude of forces in a variety of different angles.  
         [0008]     Although the night latch and/or vent stops are capable of preventing the lower sash from moving passed a certain desired position, their utility is unfortunately outweighed by their inherent clumsy composition. The night latch in the present invention improves on the prior art shortcomings by implementing a unique method of activating and inactivating the tumbler from the housing, without taking away from its utility and its aesthetic quality. In addition, the invention implements an improved button, which is used for activating the tumbler of the night latch of the present invention.  
         [0009]     2. Objects of the Invention  
         [0010]     It is an object of the present invention to provide a night latch that operates more easily than the prior art night latches.  
         [0011]     It is an object of the present invention to provide an improved night latch that is more reliable in its operation than the prior night latches.  
         [0012]     It is an object of the present invention to provide a night latch that allows the user to more readily reposition the tumbler back in an inactivated position.  
         [0013]     It is still another object of the invention to allow the user the ability of activating the tumbler without the use of multiple forces to release the tumbler.  
         [0014]     It is a still further object of the present invention to provide for a more durable night latch, so as to allow for a longer period of operability.  
         [0015]     It is still a further object of the present invention to produce a night latch with a superior button mechanism, in particular a button that does not require a separate spring to bias the protrusion of the button into the recess of the tumbler.  
         [0016]     These and other objects of the present invention will become apparent to those skilled in the art from a review from the description provided below.  
       SUMMARY OF THE INVENTION  
       [0017]     The present invention is an improved night latch or sash controlling mechanism. The improved night latch can be used with a variety of windows and doors, including, but not limited to, single hung windows, double hung windows, sliding windows and doors, etc. The windows can be of the type that moves vertically or horizontally. If the windows are to move in a vertical fashion then the windows will have upper and lower sashes situated in the frame of the windows. If the windows are to move horizontally, then the windows will have right and left sashes situated in the window&#39;s frame. A night latch for a sliding door can be installed and operated in the same manner as the sliding window, except the door will sit in the door frame rather than a window frame. More specifically, this invention is directed to be an integral part of a sliding window or door, that is simple, inexpensive, and ergonomically superior to the prior art.  
         [0018]     The present invention, as mentioned previously, is a continuation-in-part of previously filed United States patent application filed on Mar. 27, 2006 Serial #, and as such all disclosures of which are hereby incorporated by reference. The night latch of the present invention has three primary components, as in the applicants previously filed patent application, a tumbler, a button, and a housing that will accommodate the tumbler and the button. The housing is placed in a groove or recess on the face of the upper window sash. The housing is constructed so as to make for a tight, smooth, and finished appearance when inserted into the groove of the window sash. This fit will make for an aesthetically pleasing appearance.  
         [0019]     As in the applicant&#39;s previously filed application #, a tumbler is generally used as the stopping mechanism in the night latch. In general, the tumblers of other prior art are activated by applying an outside force in a multitude of ways directly to the tumbler, making for a rather difficult and sometimes impossible task. One example of this is when the spring inside the tumbler is new and rather tight. In the present invention the tumbler is activated via an improved separate button, located on the housing of the night latch. This allows the user to activate the tumbler with relative ease. The force applied can be in a downward motion, as in the present invention, or the force applied can be in an inward motion. The direction of the force applied depends on how the button is configured.  
         [0020]     In addition to the relative ease of operation of the improved night latch, the improved night latch has an active cover located either on the bottom of the housing, or on the side, which allows for installing parts inside of the housing. In the prior art the housing is open, thus exposing the inside parts, such as the tumbler and spring, to the outside weathering elements, such as moisture in the air, which could cause malfunction of the night latch, i.e. a rusty spring. In the present invention the active cover acts as a barrier, so as to impede the destructive nature of weathering.  
         [0021]     Moreover, the night latch of the present invention can be deactivated with even less effort than the prior art. If the user wished to close the night latch in the prior art, the user would have to exert an inward and downward force to deactivate the night latch. This is because the tumbler in the prior art is kept depressed via the face of the tumbler and the top plate of the housing. As mentioned previously application of these forces can prove to be rather burdensome when the night latch was fairly new. In the present improved night latch, the only force needed is a downward force; this is because of the co-action between the tensed bottom protruding portion of the button and the bottom recess portion of the tumbler. The protruding portion of the button keeps the tumbler in a locked inactivated position.  
         [0022]     The button in the present invention improves on the button of our previously filed United States patent application filed on Mar. 27, 2006 Serial #. The button in the present invention does not implement a torsion spring. In our previously filed patent application a torsion spring was implemented, which biased the protrusion of the button into the recess of the tumbler. With the present button configuration the use of a separate spring has been rendered unnecessary do to the advanced button design. In the present invention the bottom portion of the button is designed to be of such resilient nature, so as to act as a tumbler retainer when the tumbler is not in an activated position. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]      FIG. 1  is a perspective view of the night latch of the present invention set in a window frame with the tumbler exposed.  
         [0024]      FIG. 2  is a side exploded view of the night latch of the present invention with the cover not attached.  
         [0025]      FIG. 3  is a rear end view of the night latch of the present invention with the tumbler exposed.  
         [0026]      FIG. 4  is a side view of the night latch of the present invention with the tumbler exposed.  
         [0027]      FIG. 5  is side cut out view of the night of the present invention with the tumbler exposed.  
         [0028]      FIG. 6  is a top side cut out view of the night latch of the present invention with the tumbler exposed.  
         [0029]      FIG. 7  is a side cross-sectional view of the night latch of the present invention with the tumbler in a retracted position.  
         [0030]      FIG. 8  is a side cross-sectional view of the night latch of the present invention with the tumbler exposed, without guide members.  
         [0031]      FIG. 9  is a side cross-sectional view of the night latch of the present invention with the tumbler exposed, and the button released from the housing, without guide members.  
         [0032]      FIG. 10  is a perspective view of the improved bottom of the night latch of the present invention.  
         [0033]      FIG. 11  is an exploded view of the tumbler and the spring of the night latch of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0034]     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.  
         [0035]     In  FIG. 1 , the night latch of the present invention is shown generally at  10 . Night latch  10  is shown positioned inside slot  11  in stopping member  12 . The slot  11  is shown as having an oval shape, but any other suitable shape and size slot including but not limited to a square, rectangle, oval, etc. can be used depending on the shape of the latch. Preferably however, the night latch  10  of the present invention will have a housing portion similarly shaped to slot  11  as to present a clean appearance when placed in the stopping member  12 . In the present embodiment an oval shape was implemented for illustration purposes. The stopping member can be a sash, doorframe, or any other member that has another piece sliding over it, where restriction of the sliding member is desired. Tumbler  36  can be in either a raised or in a lowered position. When raised it prevents movement of the door or sash  
         [0036]      FIG. 2  is a more detailed view of the contemplated night latch. A housing  13  is generally defined by a first and second sidewall,  14  and  15  respectively, and a front and rear wall,  16  and  17  respectively. It is noted that the terms “front” and “rear” are used only for descriptive purposes and do not read on orientation of the device. Sidewalls  14  and  15  are preferably the same length, as are front and rear walls  16  and  17 , respectively, providing for a generally rectangular shape to housing  13 . Preferably, when in place within slot  11 , sidewalls  14  and  15  contact the edges of slot  11  to provide for a tight fit, and prevent a lateral movement of the night latch  10  within slot  11 . In addition, sidewalls  14  or  15  can be detachable so as to act as cover plates for accessing housing  13 . In the present embodiment sidewall  14  acts as a detachable cover plate, as seen in  FIG. 2 . In another embodiment one may implement a separate cover plate that can be placed near the front end of housing  13 .  
         [0037]     Front wall  16  can have a front flexible clip  18  and rear wall  17  can have a rear flexible clip  19 , as seen in  FIG. 4 . Each clip may extend generally in an upward fashion, originating at or near bottom surface  20  of housing  13 , and may end just below top plate  25 . In the present embodiment each clip creates a notch  22  between a lip  23  on bottom surface  24  of top plate  25 , also seen in  FIG. 4 . When night latch  10  is depressed into slot  11  on a stopping member  12 , each notch  22  can engage a portion of the stopping member  12 . This engagement can prevent vertical (front and back) movement of night latch  10  within the stopping member  12 , as well as preventing night latch  10  from being easily dislodged from slot  11 .  
         [0038]     First sidewall  14  has an inner surface  26  and outer surface  27 . Second sidewall  15  has inner surface  28  and outer surface  29 . The inner surfaces  26  and  28  can have two protrusions  30  and  31  respectively that act as guide members for tumbler  36 . This can be accomplished by setting protrusions  30  and  31  into cavity  32  located inside housing  13 , as seen in  FIG. 6 . In addition to acting as guide members for tumbler  36  protrusions  30  and  31  acts as a limiting device for tumbler  36 , i.e. tumbler  36  will extend out only the distance allowed by the coaction between protrusions  30  and  31  and grooves  44 ( a ) and  44 ( b ) of tumbler  36 . The shape of the protrusions,  30  and  31 , can be of any suitable shape including but not limited to a square, rectangle, circle, etc. In the present embodiment protrusions  30  and  31 , and their respective grooves,  44 ( a ) and  44 ( b ) are of rectangular shape. Walls  14  and  15  also can have two circular areas,  33  and  34  respectively, positioned towards rear wall  17 . Circular areas  33  and  34  are aligned along the same central axis. These circular areas are designed so as to allow tumbler  36  to rotate from a recessed position to an outwardly position. The circular areas can be any suitable circular areas known in the art including, but not limited to apertures, bores, cavities, and the like. In the present embodiment circular areas,  33  and  34  are a bore and an aperture respectively. Bored area  33  on wall  14  can be enlarged so as to allow greater contact with axle  38 , this can be achieved by affixing a hollowed out extension of bored area  33  that surrounds a partial portion of outside perimeter of bored area  33 , not shown. As mentioned previously one can also have two apertures instead of one aperture and one bored hole, as seen in  FIG. 2 .  
         [0039]     The lip  23  attached to top plate  25  is preferably at least the same size or larger and the same general shape as slot  11 . Thus, when night latch  10  is placed into slot  11 , lip  23  will contact at least the edges of slot  11 , or over spread the upper surface of the stopping member  12 . These dimensional attributes will allow for a tight fit that will exhibit a finished smooth exterior, which can be aesthetically pleasing. Although top plate  25  is referred to as a “plate”, it is understood that housing  13 , clip  18 , lip  23  and top plate  25  can be integral pieces, without any need for adhesives or assemblage.  
         [0040]     A tumbler  36  is preferably designed to fit within cavity  32  of housing  13 . Tumbler  36  may have an upper surface  37 , which is preferably smooth and/or flat, as seen in  FIG. 11 . A flat surface  37  will exhibit a more finished look for night latch  10  when it is placed in stopping member  12 . Tumbler  36  can have a front end  43  and a rear end  42 , along with side surfaces  40  and  41 . In addition, tumbler  36  can have a rotation member  38  located on rear end  42  that extends from side surface  40  to side surface  41  on tumbler  36 . Rotation member  38  can fit into areas  33  and  34 . Rotation member  38  can be any suitable structure known in the art including but not limited to a peg, axle, pin, etc. Furthermore, rotation member  38  can be two separate members affixed to tumbler  36 , such as two cylindrical pegs attached to side surfaces  40  and  41  respectively. In the present embodiment rotation member  38  is single axle. In addition rotation member can be part of tumbler  36 , or rotation member  38  can stand alone. In the present embodiment rotation member  38  is a part of tumbler  36 . By setting rotation member  38  into corresponding areas  33  and  34  will allow tumbler  36  to pivot within cavity  32 , and thus rotate from a recessed position to an extended position and have a portion exposed above the surface of stopping member frame  12 .  
         [0041]     In addition to having rotation member  38 , tumbler  36  also has two arcuate grooves  44 ( a ) and  44 ( b ) located on side surfaces  40  and  41  respectively. Grooves  44  ( a ) and ( b ) can house guide members  30  and  31 , of sidewalls  14  and  15  respectively, and thus provide an arcuate path for tumbler  36  about axis of rotation member  38 . Furthermore, grooves  44  ( a ) and ( b ) and guide members  30  and  31  can act as a restricting device for tumbler  36 , as mentioned previously. When tumbler  36  is in an activated position guide members  30  and  31  contact the bottoms of  45  ( a ) and ( b ) of grooves  44  ( a ) and ( b ), this interaction will lock guide members  30 ,  31 , and bottoms  45  ( a ) and ( b ), which will cause tumbler  36  to lock into an exposed position, thus exposing the stopping surface  52 , which will act as to prevent the sliding member from moving beyond a certain predetermined position.  
         [0042]     Tumbler  36  has a bored area  100 , which can be placed on either side of tumbler  36 , as seen in  FIG. 5 . In the present embodiment bored area  100  is located toward the rear end of side surface  40  of tumbler  36 . Bored area  100  has a wall  101 , not shown, that extends tangentially from plane  102 , not shown, to side surface  40 . In addition, bored area  100  has a circular shaped protrusion; any suitable circular shaped protrusion known in the art can be implemented including, but not limited to a peg, pin, and the like. In the present embodiment a cylindrical peg  103  that extends tangentially the exact distance of wall  101  was implemented.  
         [0043]     The force that causes tumbler  36  to rotate in an outwardly fashion, can be created by a spring. Any spring known in the art including, but not limited to coil, helical, torsion, etc. can be used. In the present embodiment, a coil spring  46  was implemented. Spring  46  has three members; the first is a coiled portion  50  that rests on cylindrical peg  103 , as seen in  FIGS. 2 and 5 . The second member is elongated portion  48 , which exerts a constant force on the inside bottom surface  20  of housing  13  and a third member, elongated portion  49 , which exerts a constant force on wall  101  in bored area  100  of tumbler  36 . The tension created by elongated portions  48  and  49  is of such a nature that the tension will be greater when tumbler  36  is depressed so as to push tumbler  36  in an outwardly fashion when button  54  is triggered.  
         [0044]     Front end  43  of tumbler  36  can have a stopping surface  52 . When exposed, stopping surface  52  will prevent movement of a sliding frame or member intending to slide over night latch  10 . Stopping surface  52  can also have a cavity portion  53 , which is a hollowed portion of front end  43  of tumbler  36 . Cavity  53  is of such dimensions so as to allow entry of protruding portion of button  55 . In addition, cavity  53  should be of such dimensions so that the integrity of tumbler  36  will not be compromised by the frequent contact of a sliding member  
         [0045]     The release of tumbler  36  from housing  13  can be controlled by an interaction between a button  54 . Button  54  can have a top surface  56  which can be in the same plane as upper surface  37  of tumbler  36 . Button  54  can reside in opening  35  of top plate  25 . Top surface  56  of button  54  can be designed to have the same shape as opening  35  of top plate  25 , however, any suitable shape known in the art including, but not limited to square, rectangle, circle, or any combination thereof. In the present embodiment, because of the rectangular look of the night latch  10 , opening  35  has a rectangular rear section and circular front tip portion. The top surface  56  of button  54  has the same basic look as opening  35 , except that top surface  56  is smaller in proportion, so as to allow movement inside opening  35 . Here, the user can access the button  54  easily. Top surface  56  of button  54  can have a groove  57 , which the user can engage with a finger, fingernail, pen, pencil, etc. or any other suitable instrument known in the art. Button  54  can be designed to move in different ways, any suitable movement known in the art but not limited to sliding, depression, etc. In the present embodiment button  54  was designed to slide in an up and down manner, within opening  35 . When the night latch is not activated, i.e. tumbler  34  is depressed; the top surface  56  of button  54  will rest toward the rear end  35   a  of opening  35  of top plate  25 . When the user wishes to activate night latch  10 , the user will apply a downward force to groove  57 , which will cause the top button  56  to slide toward the front end  59  of opening  35 , as seen in  FIGS. 4 and 6 .  
         [0046]     Improved button  54  of the present invention will now be discussed in greater detail. Drawing one&#39;s attention to  FIG. 10  one can see the button of the night latch of the present invention. Button  54  as mentioned previously may have a top surface  56  and a groove  57 . In addition, button  54  may be manufactured from any suitable material known in the art including, but not limited to resins, plastic and the like. In the preferred embodiment one manufactured button  54  out of a plastic polymer. This type of material was preferred, because of its resilient nature. In addition to having portions  56  and  57 , button  54  may also have a left portion  58  and a right portion  59 .  
         [0047]     Portion  58  may be generally rectangular in shape, which may extend from bottom surface  60  of button  54 , toward the bottom surface of housing  20 , as seen in  FIG. 7 . In the preferred embodiment portion  58  and bottom surface  20  of housing  13  do not come into contact, however, one could, if one desired, design the present invention so that surface  20  and portion  58  do contact each other. The utility of the latter embodiment is beyond the scope of the present invention. In addition, located near the top of left portion  58  of button  54  may be a recess  58   a  that contacts a bottom surface  25   a  of top plate  25  of housing  13 , as seen in  FIGS. 7, 8  and  9 . Recess  58   a  of portion  58  may be implemented so as to co-act with bottom surface  25   a  in preventing portion  58  from pivoting in an outward motion. Also located on portion  58  may be tooth-like protrusion  58   b , as seen in  FIG. 5 . Tooth-like protrusion  58   b  may be of any suitable shape known in the art, in the preferred embodiment one implemented a shape that would fit inside of recess  53  of tumbler  36 . It is pointed out that recess  53  and tooth-like protrusion  58   b  may be any suitable shape known in the art, the key element of the arrangement is that tooth-like protrusion  58   a  should be able to fit inside of recess  53  of tumbler  36 , so as to inhibit movement of tumbler  36 , until tumbler  36  is activated. Portion  58  and portion  59  are joined at an apex  61 , best observed in  FIGS. 7, 8  and  9 .  
         [0048]     Portion  59  of button  54  is generally rectangular in shape, and it extends in a similar manner as that of member  58 , that is to say portion  59  also extends from bottom surface  60  of button  54 , toward the bottom surface of housing  20 , as seen in  FIG. 7 . Although portion  59  and portion  58  are both generally rectangular in shape, portion  58  is generally slightly broader than portion  59 . The reason for the dimension difference, in the preferred embodiment, between portion  58  and portion  59 , is twofold. First, portion  58  has to support tooth-like protrusion  58   b , and second, portion  59  provides the biasing force required to retain tumbler  36  in a retracted position, hence, portion  59  needs to be more flexible than portion  58 . It is this constant force that keeps tumbler  36  in a depressed state. One may however, implement different dimensions for either portion  58  and  59 , if one desired.  
         [0049]     In another embodiment one may implement two wings  63  and  64  on both side surfaces  61  and  62  respectively of top button portion  56 , as in the previously filed United States patent application filed on Mar. 27, 2006 Serial #. Wings  63  and  64  can be of any suitable shape known in the art including but not limited to a square, rectangle, oblong, etc. In that type of embodiment two oblong wings may be implemented. Wings  63  and  64  are allowed to move in a linear back and forth manner, inside slots  68  and  69  respectively, not shown, which are located on sidewalls  14  and  15  respectively. Slots  68  and  69  can be of any suitable shape known in the art including but not limited to square, rectangle, oblong, etc. In the present embodiment two rectangular slots were implemented.  
         [0050]     On bottom surface  20  of housing  13  there exists a ramp like protrusion  77  with an aperture  78  at its highest point, as seen in  FIGS. 7 and 8 . Aperture  78  of protrusion  77  acts as a housing for one of cover plate  14 &#39;s pins,  79 . Pins  79  and pin  80  are located on the bottom of inside surface  26  and the top rear end of inside surface  26  respectively, as seen in  FIG. 2 . When access to the inside of housing  13  is needed, cover plate  14  can be snapped out of place. When access to inside of housing  13  is no longer required cover plate  14  can be snapped back into place by inserting pin  79  into aperture  78  of protrusion  77 , and inserting pin  80  into aperture  81 , located on the upper side wall  82  of housing  13 , thus closing housing  13 .  
         [0051]     In another embodiment one may have tumbler  36  with a tooth-like protrusion and button portion  58  with a recess. The functionality of the vent stop would not be altered with this type of embodiment.  
         [0052]     When the user desires to activate tumbler  36  so as to cease movement of sliding window member, the user will exert a downward force, greater than that of portion  59 , on groove  57 , of button  54 . This force will cause button  54  to move in a direction opposite that of the stored potential energy of portion  59 , thus causing tooth-like protrusion  58   b  of portion  58  of button  54  to disengage cavity  53  of tumbler  36 . When tumbler  36  is free to pivot on axle  38 , the upward force of spring  46  will cause tumbler  36  to rotate in an outwardly direction until rectangular guides  30  and  31  meet with bottoms  45 ( a ) and  45 ( b ) of grooves  44 ( a ) and  44 ( b ), at which time stopping surface  53  of tumbler  36  will be exposed, thus preventing sliding window member from opening any further.  
         [0053]     As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense. In the view above it will be seen that several objects of the invention are achieved and other advantageous results attained.