A device may limit opening of a sash hingedly coupled to a master frame, and includes: a bracket attached to the sash; a first arm having a first end pivotally coupled to the bracket; a second arm having a first end pivotally coupled to the first arm's second end; means for biasing the second arm into a retracted position; and a release assembly. The release assembly is secured to the master frame and includes a hook pivotable between a first position and a second position, which, in the first position, may be releasably received in an opening in the second end of the second arm when the second arm is in the retracted position, as the sash is closed and received within the master window frame The second arm is disengaged from the hook, permitting full opening of the sash, when the hook is pivoted into the second position.

FIELD OF THE INVENTION 
     The present invention relates to improvements in window opening control devices, and more particularly to a device that is capable of limiting the travel of a casement window. 
     BACKGROUND OF THE INVENTION 
     One safety concern for children, with respect to the windows that may be installed into residential homes and other buildings, are its features that may serve to prevent accidental egress and serious injury from a fall. One preventative feature is the height that the windows are installed above the floor, which prevents toddlers from accidentally falling out, and inhibits small children from creatively seeking to observe the outside view from the sill of the window, which could result in an accidental fall therefrom. 
     Opening control devices for windows (WOCDs), which serve to releasably limit the travel that a window may undergo to a relatively small amount, which may be roughly four inches, are another feature that has been employed on sliding sash windows for that reason. They have also been utilized thereon to prevent unauthorized entry into the dwelling from the outside by an intruder. However, preventative measures in the form of WOCDs have not been pursued as vigorously for casement windows, which typically are hingedly connected in some fashion to the master window frame. 
     As building codes have sought to regulate the construction industry to improve child safety through the use of such devices (see e.g., ASTM F2090-10: “Standard Specification for Window Fall Prevention Devices with Emergency Escape (Egress) Release Mechanisms”), tradeoffs have been proposed to reduce the height restrictions for window installations where such devices are utilized. But such lessening of these window height requirements only serves to place greater importance on the integrity of the WOCDs, particularly their ability to automatically reset themselves, after having been manually released to open the casement window beyond its restricted range of movement. 
     The window opening control device of the present invention is uniquely adapted to not only limit the range of travel of the casement window to prevent accidental falls therefrom, and to automatically reset itself, but to also avoid the necessity of having to remove the screen from the window in order for the device to function properly. 
     OBJECTS OF THE INVENTION 
     It is an object of the invention to provide a window opening control device that may releasably limit the travel of a casement window to an amount preventing accidental egress therefrom. 
     It is another object of the invention to provide a window opening control device for a casement window that is easily released to permit full travel of the casement window when desired. 
     It is a further object of the invention to provide a safety switch for a window opening control device for a casement window that prevents tampering by young children who may seek to impermissibly operate the safety device. 
     It is another object of the invention to provide a window opening control device for a casement window that automatically resets the device, after the window has been moved back to the closed position. 
     Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings. 
     SUMMARY OF THE INVENTION 
     A device may limit opening of a sash window that is hingedly coupled to a master window frame, and may include: a bracket attached to the sash; a first arm having a first end pivotally coupled to the bracket; a second arm having a first end pivotally coupled to the second end of the first arm; a means for biasing the second arm into a retracted position; and a release assembly. The release assembly may be secured within the master window frame and may include a hook member that is pivotable between a first position and a second position. 
     With the hook member occupying the first position, the hook portion thereon may be releasably received in an opening in the second end of the second arm, when the first and second arms are in the retracted position, and the sash is closed and received by the master window frame. 
     The first arm may normally occupy its retracted position, with respect to the bracket that is fixedly secured to the sash, by rotating downward into a vertically oriented position, and may be limited to that position through the prevention of any over-travel by a stop protruding from the bracket. The second arm may be configured to normally occupy its retracted position, with respect to the vertically oriented first arm and the bracket, by being biased against gravity to rotate upwardly to be positioned, and travel limited by a stop on the first arm, to occupy a somewhat vertical position, being at a small acute angle with respect to the first arm. 
     Once the hook portion of the hook member has been releasably received within the opening in the second end of the second arm, as described above, the sash may be opened, and the amount that it may be opened will be travel-limited according to the length of the first and second arms. The sash of the casement window being travel limited in this manner will prevent a small child from accidentally falling through the gap between the sash and the master window frame. When the user desires to open the window even further, the second arm may be disengaged from the hook of the release assembly, by rotating the hook to be in the second position. 
     The hook may be configured to extend from a graspable switch member, in order for a user's hand to more easily cause its pivotal movement between the first and second positions. The hook and switch member may be installed directly into a master window frame that is particularly configured to receive its envelope and permit pivotal movement therein, or it may instead be received within a base member that itself is adapted to be received within a simple opening in the master window frame and secured thereat. 
     The combination of the switch member and base member may serve to enable additional functionality. The switch member may be configured to receive a spring biased safety button therein, which may be slidable between a protruding position and a depressed position. The safety button may be configured to inhibit pivoting of the switch member and hook combination from its first position, when the button occupies its spring biased outwardly disposed position. When the button is depressed, pivoting of the switch member is no longer inhibited, and it may be pivoted into the second position to release the second arm from the hook member. The helical spring may also have its ends adapted to provide torsional biasing of the switch member relative to the base member, so that when the user releases their grasp of the switch member, it may be biased so that the combination switch member and hook member occupy the first position, and may readily accommodate engagement with the catch assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a perspective view of the window opening control device of the present invention, installed upon a casement window master frame and its sash window, and with the device being used to releasably secure the window sash to prevent further travel of the opened window beyond the safe limit. 
         FIG. 2  illustrates the window opening control device and casement window of  FIG. 1 , but with the device having been released to permit further travel of the opened window sash. 
         FIG. 2A  is an enlarged detail view of the release assembly on the window frame and the catch assembly on the sash, as seen in perspective view of  FIG. 1 . 
         FIG. 2B  is an enlarged detail view of the bracket of the catch assembly of  FIG. 1 , showing the possible use of backing plates to accommodate installation on a sash with a different profile. 
         FIG. 2C  is a side view of the release assembly and a portion of the catch assembly, as installed on the casement window of  FIG. 1 . 
         FIG. 2D  is a front view of the release assembly protruding through the master frame of the casement window of  FIG. 2C . 
         FIG. 2E  is a top view of the release assembly of  FIG. 2D , shown by itself. 
         FIG. 2F  is a perspective view of the release assembly of  FIG. 2E , but shown with the switch member cut away. 
         FIG. 2G  is a bottom perspective view of the switch member. 
         FIG. 2H  is a perspective view of the assembled hook member, the turning switch, and the safety button of the present invention. 
         FIG. 3  illustrates the catch assembly and the release assembly of the window opening control device of  FIG. 2 , with the casement window omitted from the view, and with the catch assembly releasably secured to the release assembly, the arms of the catch assembly being in the retracted position, and with the sash having been closed with respect to the master frame. 
         FIG. 4  illustrates the catch assembly and the release assembly of the window opening control device of  FIG. 3 , but with the arms of the catch assembly shown extended, for when the sash is opened with respect to the master frame, and thereby travel limited. 
         FIG. 4A  illustrates a reverse perspective view of the release assembly of  FIG. 4 , where the safety button has not been depressed. 
         FIG. 4B  is an enlarged detail view of the release assembly retaining the second arm of the catch assembly, as seen in  FIG. 4 . 
         FIG. 5  illustrates the catch assembly and the release assembly of the window opening control device of  FIG. 4 , but with the safety button having been depressed, and the switch member pivoted to release the hook of the release assembly from the opening of the second arm of the catch assembly. 
         FIG. 5A  illustrates a reverse perspective view of the release assembly of  FIG. 5 , where the safety button has been depressed, and the switch member pivoted. 
         FIG. 5B  is an enlarged detail view of the release assembly shown in  FIG. 5 . 
         FIG. 6  illustrates the catch assembly and the release assembly of the window opening control device of  FIG. 5 , but with arms of the catch assembly moving into the retracted position as a result of spring biasing. 
         FIG. 7  is an exploded view of the parts used for assembly and installation of the opening control device of the present invention. 
         FIG. 8  is a perspective view of the bracket of the catch assembly of the opening control device of the present invention. 
         FIG. 8A  is a front view of the bracket of the catch assembly of  FIG. 8 . 
         FIG. 8B  is a side view of the bracket of the catch assembly of  FIG. 8 . 
         FIG. 8C  is an end view of the bracket of the catch assembly of  FIG. 8 . 
         FIG. 9  is a perspective view of the first arm of the catch assembly of the opening control device of the present invention. 
         FIG. 9A  is a front view of the first arm of the catch assembly of  FIG. 9 . 
         FIG. 9B  is a side view of the first arm of the catch assembly of  FIG. 9 . 
         FIG. 9C  is an end view of the first arm of the catch assembly of  FIG. 9 . 
         FIG. 10  is a perspective view of the second arm of the catch assembly of the opening control device of the present invention. 
         FIG. 10A  is a front view of the second arm of the catch assembly of  FIG. 10 . 
         FIG. 10B  is a side view of the second arm of the catch assembly of  FIG. 10 . 
         FIG. 10C  is an end view of the second arm of the catch assembly of  FIG. 10 . 
         FIG. 11  is a perspective view of the torsion spring of the catch assembly of the opening control device of the present invention. 
         FIG. 11A  is a front view of the torsion spring of the catch assembly of  FIG. 11 . 
         FIG. 11B  is a side view of the torsion spring of the catch assembly of  FIG. 11 . 
         FIG. 11C  is an end view of the torsion spring of the catch assembly of  FIG. 11 . 
         FIG. 12  is a perspective view of the rivet of the catch assembly of the opening control device of the present invention. 
         FIG. 12A  is a front view of the rivet of the catch assembly of  FIG. 12 . 
         FIG. 12B  is a side view of the rivet of the catch assembly of  FIG. 12 . 
         FIG. 12C  is an end view of the rivet of the catch assembly of  FIG. 12 . 
         FIG. 13  is a perspective view of the base member of the release assembly of the opening control device of the present invention. 
         FIG. 13A  is a front view of the base member of the release assembly of  FIG. 13 . 
         FIG. 13B  is a side view of the base member of the release assembly of  FIG. 13 . 
         FIG. 13C  is an end view of the base member of the release assembly of  FIG. 13 . 
         FIG. 14  is a perspective view of the switch member of the release assembly of the opening control device of the present invention. 
         FIG. 14A  is a front view of the switch member of the release assembly of  FIG. 14 . 
         FIG. 14B  is a side view of the switch member of the release assembly of  FIG. 14 . 
         FIG. 14C  is an end view of the switch member of the release assembly of  FIG. 14 . 
         FIG. 15  is a perspective view of the hook member of the release assembly of the opening control device of the present invention. 
         FIG. 15A  is a front view of the hook member of the release assembly of  FIG. 15 . 
         FIG. 15B  is a side view of the hook member of the release assembly of  FIG. 15 . 
         FIG. 15C  is an end view of the hook member of the release assembly of  FIG. 15 . 
         FIG. 16  is a perspective view of the safety button of the release assembly of the opening control device of the present invention. 
         FIG. 16A  is a front view of the safety button of the release assembly of  FIG. 16 . 
         FIG. 16B  is a side view of the safety button of the release assembly of  FIG. 16 . 
         FIG. 16C  is an end view of the safety button of the release assembly of  FIG. 16 . 
         FIG. 17  is a perspective view of the spring of the release assembly of the opening control device of the present invention. 
         FIG. 17A  is a front view of the spring of the release assembly of  FIG. 17 . 
         FIG. 17B  is a side view of the spring of the release assembly of  FIG. 17 . 
         FIG. 17C  is an end view of the spring of the release assembly of  FIG. 17 . 
         FIG. 18A  shows the decal of the exploded view of  FIG. 7  that may be used to position holes on the sash for proper positioning thereon of the catch assembly of the opening control device of the present invention. 
         FIG. 18B  shows the decal of  FIG. 18B  being further used to coordinate the hole positions on the sash with proper positioning of the holes on the master window frame, for proper mounting thereon of the release assembly. 
         FIG. 19  is an exploded view of the parts forming a second embodiment of the opening control device of the present invention, including a V-shaped torsion spring. 
         FIG. 20  illustrates the catch assembly and the release assembly of the second embodiment of the window opening control device of the present invention, with the casement window omitted from the view, and with the catch assembly releasably secured to the release assembly, the arms of the catch assembly being in the retracted position, and with the sash having been closed with respect to the master frame. 
         FIG. 21  illustrates the catch assembly and the release assembly of the window opening control device of  FIG. 20 , but with the arms of the catch assembly shown extended, for when the sash is opened with respect to the master frame, and thereby travel limited. 
         FIG. 22  is a first perspective view of the base member of the release assembly of the second embodiment of the opening control device of the present invention. 
         FIG. 22A  is a second perspective view of the base member of  FIG. 22 . 
         FIG. 22B  is a third perspective view of the base member of  FIG. 22 . 
         FIG. 22C  is a fourth perspective view of the base member of  FIG. 22 . 
         FIG. 22D  is a fifth perspective view of the base member of  FIG. 22 . 
         FIG. 22E  is a sixth perspective view of the base member of  FIG. 22 . 
         FIG. 23  is a front view of the base member of  FIG. 22 . 
         FIG. 23A  is a rear view of the base member of  FIG. 22 . 
         FIG. 24  is a first side view of the base member of  FIG. 22 . 
         FIG. 24A  is a second side view of the base member of  FIG. 22 . 
         FIG. 25  is an end view of the base member of  FIG. 22 . 
         FIG. 26  is a first perspective view of the switch member of the release assembly of the second embodiment of the opening control device of the present invention. 
         FIG. 26A  is a second perspective view of the switch member of  FIG. 26 . 
         FIG. 26B  is a third perspective view of the switch member of  FIG. 26 . 
         FIG. 26C  is a fourth perspective view of the switch member of  FIG. 26 . 
         FIG. 26D  is a fifth perspective view of the switch member of  FIG. 26 . 
         FIG. 26E  is a sixth perspective view of the switch member of  FIG. 26 . 
         FIG. 27  is a front view of the switch member of  FIG. 26 . 
         FIG. 27A  is a rear view of the switch member of  FIG. 26 . 
         FIG. 28  is a first side view of the switch member of  FIG. 26 . 
         FIG. 28A  is a second side view of the switch member of  FIG. 26 . 
         FIG. 29  is a first end view of the switch member of  FIG. 26 . 
         FIG. 29A  is a second end view of the switch member of  FIG. 26 . 
         FIG. 30  is a perspective view of the hook member of the release assembly of the second embodiment of the opening control device of the present invention. 
         FIG. 31  is a front view of the hook member of  FIG. 30 . 
         FIG. 32  is a side view of the hook member of  FIG. 30 . 
         FIG. 33  is an end view of the hook member of  FIG. 30 . 
         FIG. 34  is a perspective view of the torsion spring of the catch assembly of the release assembly of the second embodiment of the opening control device of the present invention. 
         FIG. 35  is a front view of the torsion spring of  FIG. 34 . 
         FIG. 36  is a side view of the torsion spring of  FIG. 34 . 
         FIG. 37  is an end view of the torsion spring of  FIG. 34 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a perspective view of the catch assembly of the window opening control device of the present invention having been installed upon a master frame and sash of a casement window. The device is being used thereon to releasably secure the sash to the master frame to prevent further travel of the opened window sash beyond the safe limit. Depressing of a safety button and pivoting of a switch member causes release of the device to permit further travel of the opened window sash, as seen in  FIG. 2 . 
     The two main assemblies of the opening control device of the present invention are seen in the enlarged detail view of  FIG. 2A , and consist of the catch assembly  100 , and the release assembly  200 . The catch assembly  100  and release assembly  200  may be secured to the sash window  11  and the master window frame  21 , respectively, and are discussed further hereinafter. 
     The catch assembly  100  may consist of a bracket  110 , a first arm  120 , a second arm  130 , and a torsion spring  140 . The bracket  110  is shown in detail within  FIGS. 8-8C . Bracket  110  may be a generally flat plate that may be pocketed to reduce weight in-between certain features that are necessary to enable use of the bracket. Bracket  110  may include a pair of mounting holes  111 A and  111 B, which may be formed with a countersink to accommodate flush head mounting screws therein, in order to suitably mount the bracket to the side of the sash  11 . A hole  112  in the bracket  110  may be used for pivotal mounting thereto of the first arm  120 , which may be pivotally mounted using a rivet  159 , or other suitable pivotal fastening means. The bracket  110  may include a protruding stop member thereon, which may be used to limit travel of the pivotally mounted first arm  120  with respect to the bracket, when the arm is in the retracted position. The mounting holes  111 A and  111 B may be symmetrically positioned in the bracket, and may be symmetrically positioned with respect to the hole  112  that is used for pivotal mounting of the first arm  120 , which may be centered therein. With the hole  112  being centrally positioned, the pivotal stop may be located towards one end of the bracket  110 , to reduce loading of those features of the bracket. In order to be able to use the bracket for mounting to either a left-hand or a right-hand sash of the casement window, there may be a first pivotal stop  113 A located at one end of the bracket  110 , and a second pivotal stop  113 B located at the other end of the bracket. Each of the stops  113 A and  113 B of bracket  110  of the catch assembly  100  may have a “V” shaped cavity formed by a slanted surface  113 S ( FIG. 8 ) of the stop, which works for guiding automatic alignment of the first arm  120  when the catch assembly  100  is biased back towards the sash  11 , and thereafter the stop  113  completely inhibits further rotation of the first arm  120  at the fully retracted position with respect to bracket  110 . 
     The first arm  120  is shown in detail in  FIGS. 9-9C , and may be an elongated thin plate member, which may be formed of plastic, metal, or any other suitable material. Proximate to the first end  121  of the arm  120  may be a hole  123  usable for pivotal mounting of the arm to the hole  112  of bracket  110 . Hole  123  may be an eccentric or slotted hole, through which the first arm  120  is riveted with the bracket  110  of catch assembly  100  via the rivet  159 . It provides free movements of the first arm  120  in all directions when the first arm  120  retracts to the sash  11  when the catch assembly  100  is unlocked from the release member  200 . Proximate to the second end  122  of the first arm  120  may be a hole  124  for the pivotal mounting thereto of the second arm  130 . Also proximate to the second end  122  may be a recess  126  in the side of the plate, which may be generally flat at a central portion. The first arm  120  may have a stop  125  positioned thereon to be in proximity to hole  124 . The stop could simply be a mechanical fastener that is fastened to the plate, such as a rivet or a nut and bolt. Alternatively, the stop could be a protrusion that is integral with the plate or bonded thereto, or the stop could be a portion of the plate being stamped and raised to protrude beyond the flat plane of one side of the arm. The latter option is shown in  FIG. 9A , which may be seen to produce a straight edge for the stop that may generally be aligned with the position of the edge of the second arm  130  where it is to be restrained in the retracted position. 
     The second arm  130  is seen in detail within  FIGS. 10-10C , and may, in general, be constructed similar to first arm  120 . Second arm  130  may be an elongated thin flat plate member, with a hole  133  proximate to its first end  131 , to be usable for pivotal mounting of the second arm to hole  124  of the first arm  120 . At the first end  131  of the second arm  130 , a small protrusion  134  may protrude orthogonally from the side of the arm, and may be formed by any of the means cited above for producing stop  125 . The protrusion  134  shown within  FIG. 10  is shown as a small tab at the first end  131  that is bent at roughly a 90 degree angle. The protrusion  134  works as a stop to limit the over rotation of the second arm  130  with respect to the first arm  120 , and is received in the recess  126  of the first arm  120  when the sash is to maximum limit opening position, which his discussed further hereinafter. The second end  132  of the second arm  130  may have a shaped opening  135  therein, which may be generally rectangular, and which may further have a notch  135 N therein, both of which are discussed later as to the operation of the opening control device. 
     The pivotal mounting of the second arm  130  to the first arm  120  may utilize a simple rivet or other mechanical fastener, and one of many different varieties of springs, which may be a tension spring or a torsion spring. Merely to be exemplary, use of torsion spring  140  and rivet  150  is utilized herein. An exemplary torsion spring  140  is illustrated within  FIGS. 11-11C , and may include a small number of helical windings  140 W or even just a portion of one winding that may terminate in a first end  141  via a radial portion  141 R, and in a second end  142 . The first and second ends  141  and  142  may be used to bias the second arm  130  with respect to the first arm  120 . (An alternative V-shaped torsion spring  340  is disclosed hereinafter discussed alternate embodiment). 
     In this exemplary arrangement, a rivet  150 , which is shown in detail within  FIGS. 12-12C , may have a first post  151  extending from the head  153 , and a second post  152  telescoping therefrom. Pivotal mounting of the first and second arms  120  and  130  may be achieved by first receiving the helical windings  140 W of the torsion spring  140  upon the first post  151  of rivet  150 , such that its radial portion  141 R of the first end  141  is received through opening  153 P in the head  153  of the rivet  150  (see  FIG. 7  and  FIG. 3 ). Next, the second arm  130  may be mounted upon the rivet  150  such that hole  133  of the second arm is received upon, and sized to be pivotal with respect to, the first post  151  of the rivet. The first arm  120  may then be mounted upon the rivet  150  such that hole  124  of the arm is received upon its second post  152 . The side of the arm may abut the shoulder  151 S formed by the side of the post  151  and the post  152 . The second end  142  of torsion spring  140  may loop about the side of the elongated flat plate of the first arm, as seen for example in  FIG. 4 . The post  152  may then be bucked to fixedly secure the first arm  120  to the shoulder  151 S, so that there will be no relative motion therebetween. Instead of relying upon the bucked post  152  to fixedly secure the first arm  120  to the rivet  150 , the post  152  may have a flat side  152 D, as seen in  FIG. 12A , to form a D-shaped profile, which may be mated to a correspondingly keyed opening  124 D ( FIG. 9A ) that may be used instead of the plain round hole. 
     Therefore, as seen in  FIG. 2A , when the bracket  110  of catch assembly  100  is properly mounted to the sash (i.e., with the bracket generally oriented in the vertical direction and using backing plate(s)  110 A/ 110 B that are shown in  FIG. 2B  to accommodate different sash/frame profiles), the first arm  120  may normally pivot downwardly (clockwise in the view) about the bracket due to gravity, until reaching the stop  113 A of the bracket. At the same time, torsional biasing provided by torsion spring  140  may cause the second arm  130  to pivot upwardly (counterclockwise in the view), in opposition of the force of gravity, until the side of the second arm contacts the stop  125  on the first arm  120 . Without any forces acting upon the catch assembly  100 , it may normally occupy this retracted position that is illustrated within  FIG. 2A . 
     An exemplary release assembly  200  is shown separately in  FIG. 4A , but in its simplest form it may instead consist of a hook element configured to be pivotally received in the master window frame, where a hook portion of the element may be configured to engage the shaped opening  135  in the second end of the second arm  130 , and be disengaged therefrom through its pivotal motion within the master window frame. This pivotal movement of this hook element that enables engagement within the opening and disengagement therefrom of its hook portion, especially using the notch  135 N in the second arm  130 , may be seen in viewing  FIGS. 4B and 5B . This simple version of the hook element may be a slightly modified version of the combination of the hook member  210  and base member  230  that are discussed hereinafter. 
     For ease of manufacturing and/or other reasons, this simplified hook element may be replaced by the combination of the separate hook member  210  that is shown within  FIGS. 15-15C  and the separate graspable switch member  220  that is shown within  FIGS. 14-14C . 
     The hook member may take many different shapes, however, the exemplary hook member  210  shown in  FIG. 15  may be a narrow, thin-shaped material that is formed to have a hook portion  212  extending from one end of its shank  211 . The other end of the shank  211  may have an eye formed thereat, or it may instead be formed with a return flange  214  that extends from a cross-member  213  to create a clasp portion  210 C. The clasp portion  210 C may be fixedly secured to a corresponding retaining member  222  formed within a recess  220 R of the switch member  220 , so that the angled hook portion  210 C of hook  210  protrudes outwardly therefrom (see  FIG. 2H ). The length of the shank  211  and its shape may be particularly formed so as to permit the hook portion  212  to be somewhat flexible with respect to the clasp portion  210 C, after it has been secured to the retaining member  222  of the switch member  220 . The clasp portion  210 C of hook member  210  may be fixedly secured within the corresponding recess  220 R of the switch member  220  using a friction fit, or using adhesive, or mechanical fasteners, or any suitable fastening means or combination thereof. 
     The shaft  221  of the switch member  220  may be formed to be pivotally received within a corresponding opening in the window master frame, and such an opening may be added to a window that is already installed and in service in a dwelling. However, to more easily accommodate installation of the release assembly  200  within the master frame of a newly manufactured window, and to further accommodate additional features of the opening control device of the present invention, the switch member  220  may instead be formed to be pivotally received within a base member  230 , which is illustrated within  FIGS. 13-13C . 
     The base member  230  may have a correspondingly shaped shaft  231  that extends from a flange  232 . The flange  232  may have a pair of holes  233 A and  233 B formed therein to receive fasteners for mounting of the base member to the master window frame  21 , as seen in  FIG. 2C ,  FIG. 2D  shows the shaft  231  of the base member  230  installed within, and protruding from, the opening in the master window frame. 
     The shaft  221  of the switch member  220  may have a stop  223  protruding therefrom ( FIG. 14 ), which may serve to limit pivotal travel of the switch member to 90 degrees of travel within the shaft  231  of the base member  230  ( FIGS. 4A and 5A ). The travel of the switch member  220  may be so limited by a pair of corresponding stops formed within the hollow of the shaft  231  of the base member  230 . 
     As an additional safety precaution, to better prevent a mischievous child from rotating the switch member  220  to disengage the opening control device to open the window fully, the device of the current invention may furthermore include a safety button  240 , which is illustrated within  FIG. 16-16C , and which may be biased by the helical spring  250  that is shown within  FIGS. 17-17C . The safety button  240  may have a cylindrical head portion  240 H, from which may extend two pairs of legs—a first pair of legs,  241 A and  241 B, and a second pair of legs,  242 A and  242 B. The safety button  240  may also have a post  243  protruding away from the bottom of the head portion  24011 , upon which may be received the first end  251  of the helical spring  250 . 
     This combination of helical spring  250  and safety button  240  may be received within the opening  224  in the shaft of the switch member  220 , such that the pairs of legs are slidably received within corresponding elongated recesses therein, which may serve to prevent rotation of the safety button with respect to the switch member. The second pairs of legs,  242 A and  242 B, as seen in  FIG. 16 , which may be longer than the first pair of legs, may have respective outwardly extending flanges  242 A F  and  242 B F . 
     Although it may be understood by one skilled in the art that other features may be used to similarly accomplish functional mating of the safety button  240 , the switch member  220 , and the base member  230 , the second pair of legs  242 A and  242 B of the safety button may herein be received through correspondingly shaped openings  225 A and  225 B in the switch member ( FIGS. 7 and 14A ), to secure the safety button to the switch member. The second pair of legs will need to be elastically deflected inwardly in order for the outwardly extending flanges  242 A F  and  242 B F  of the legs to be received through the opening  224  in the shaft  221  of the switch member  220 . Once having passed therethrough, the legs would naturally deflect back to their undeformed position, as seen in  FIG. 16A , and may thereby secure the safety button  240  with respect to the switch member  220 , as a portion of the outwardly extending flanges  242 A F  and  242 B F  of the legs would now overhang beyond the diametrical periphery of the shaft  221  (see  FIGS. 14C and 16B ). The helical spring  250  retained between the safety button  240  and the base member  230  may serve to normally bias the button to have a portion protrude outwardly beyond the graspable handle portion  226  of the switch member  220  ( FIG. 4A ). 
     This subassembly—the switch member  220 , the safety button  240 , and the spring  250 —may be coupled with the base member  230 , with the shaft  221  of the switch member being received within the opening  234  of the shaft  231  of the base member  230 . The second pair of legs  242 A and  242 B may again need to be elastically deflected inwardly in order for the outwardly extending flanges  242 A F  and  242 B F  thereon that protrude beyond the diametrical periphery of the shaft  221 , to be received through the opening  234  in the shaft  231  of the base member  230 . The outwardly extending flanges  242 A F  and  242 B F  may also be aligned to be received through the correspondingly shaped openings  235 A and  235 B in the base member (see  FIG. 7 , and  FIGS. 13A ,  14 A, and  16 B). Once having passed therethrough, the second pair of legs would again naturally deflect outwardly back to their undeformed position and would extend slightly beyond the periphery of the opening  234  ( FIG. 13A ), to thereby secure the subassembly of the switch member  220 , spring  250 , and safety button  240  with respect to the base member  230 . In addition, with the formation of the shaped openings  235 A and  235 B in the base member, the lateral extent of which may protrude in the axial direction to be slightly beyond the point where the outwardly extending flanges  242 A F  and  242 B F  overhang the periphery of the opening  234  of the shaft  231 , pivoting of the switch member relative to the base member may thereby be inhibited. This functions as a safety—a means of preventing inadvertent actuation of the release member of opening control device, by some person not familiar with the device (i.e., a child-proof safety). However, by depressing the safety button  240  to overcome the biasing by spring  250 , the portion of the outwardly extending flanges  242 A F  and  242 B F  of the second pair of legs that were still nested within the lateral extent of the openings  235 A and  235 B in the base member, may now protrude beyond its extent, and thus the switch member is then free to pivot until such pivoting is limited by the aforementioned stops, being after roughly 90 degrees of rotation (see  FIGS. 2F ,  2 G, and  2 H). 
     Another additional feature that may be incorporated into release assembly  200  may be the further provision that the helical compression spring  250  that is used to normally bias the safety button  240  outwardly from the opening  224  in the switch member  220 , may also be formed to have its first and second ends  251  and  252  be usable for providing torsional biasing of the switch member  220  relative to the base member  230 . The radial over-center portion  253  of spring  250  at its first end  251  ( FIG. 17C ) may be received in the groove  243 G in the post  243  of the head  240 H of the safety button  240  ( FIG. 16 ). Also, the outwardly extending hook portion  254  at the second end  252  of the spring  250  may similarly be restrained within a portion of the base member  230 . Therefore, when the safety button  240  of the release assembly  200  is depressed and the switch member  220  is manually pivoted 90 degrees to thereby also pivot hook portion  212  ( FIG. 5A ), after the user releases his/her grip from the switch member, the dual-biasing spring  250  may then serve to bias the switch member to counter-rotate the 90 degrees, and as well as serve to bias the safety button to translate outwardly to once again be positioned as seen in  FIG. 4A . 
     Operation of the opening control device of the present invention may thus be understood by initially viewing  FIG. 2 . With the catch assembly  100  shown in its normally retracted position on window sash  11 , as described hereinabove, the opened window sash may then be closed, which may serve to bring the catch assembly on the sash into proximity with the release assembly  200  on the master window frame, and cause engagement between the hook portion  212  of the hook member  210  and the shaped opening  135  of the second arm  130 . This is illustrated within  FIG. 3 , in which the sash and the master window frame are not shown, to better illustrate the engagement therebetween, which occurs automatically through the mere closing of the window. The flexibility of the shank  211  of the hook  210  may serve to aid in the engagement therebetween, as the approaching side of the second arm  130  may cause the angled hook portion  212  to deflect out of its way, and then it may deflect back, as the opening  135  in the arm reaches the hook portion  212 . The generally rectangular shape of the opening  135  in the second arm  130  may also serve to better accommodate capture of the hook portion  212  of the shank  211  of hook member  210 , which will be protruding substantially orthogonally from the master window frame  21 . 
     When the user opens the window, the bracket  110  on the sash moves away from the release assembly  200  on the master window frame. The engagement between the hook portion  212  of the hook member  210  and the shaped opening  135  of the second arm  130  serves to overcome the torsional biasing of the spring  140 , so that increasing distance between the sash  11  and master frame  21  ( FIG. 1 ) results in the extension of the first and second arms  120  and  130 , as seen in  FIG. 4 . (Note, recess  126  on first arm  120  and small tab  134  on second arm  130  may prevent over-travel therebetween). The length of the first and second arms  120  and  130  may be sized so that this limited travel of the sash  11  is small enough to prevent a child from accidentally falling through the opening, and may be roughly four inches. 
     As seen in  FIGS. 1 and 2 , the opening control device may be positioned on an upper part of the sash and master window frame to make it more difficult for a small child to reach the release assembly. When an adult desires to open the window beyond the travel limited position of  FIG. 1 , the safety button  240  of the release assembly  200 , as seen in  FIG. 4A , may be depressed and the switch member  220  may be rotated, so that it appears as shown in  FIG. 5A . This results in the hook portion  212  of hook member  210  moving from its initial engaged position, as seen in  FIG. 4B , to the disengage position, as seen in  FIG. 5B . Note that the notch  135 N in the opening  135  of the second arm  130  may be shaped as shown in  FIG. 10A , so that with the second arm extended as seen in  FIG. 4 , rotation of the hook member  210  would not tend to cause its hook portion  212  to jam against the side of second arm, and may freely exit from the opening  135  through the notch, as shown in  FIG. 5B . The hook member may thus be freely rotated from its first hooked position, wherein the hook  212  of the release assembly is connected with the second arm of the catch assembly, to its second unhooked or position. Once the hook  210  is disengaged, retraction of the arms may occur, where the force of gravity may cause the first and second arms  120  and  130  to drop vertically, and the second arm may also pivot with respect to the first arm, due to biasing by spring  140 , and both may move away from the release assembly  200 , as seen in  FIG. 6 , until reaching the retracted position seen in  FIG. 2 . The sash may now be fully opened. 
     An alternate embodiment of the catch assembly  100  and release assembly  200  may be catch assembly  101  and release assembly  201  that is formed using component parts being generally the same as those in  FIG. 7 , but with some minor adjustments have been made thereto, and with the modified parts being shown within the exploded view of  FIG. 19 . 
     The torsion spring  140  of  FIG. 7  and  FIGS. 11-11C  may be replaced by torsion spring  340 , which is shown in detail within  FIGS. 34-37 . Torsion spring  340  may include a small number of helical windings  340 W that may terminate in a first leg  341  and a second leg  342 . At the end of the first leg  341  being distal from the windings may be formed a hook portion  341 H, and at the end of the second leg  342  may be formed a hook portion  342 H. The first and second legs  341  and  342  may be used to bias the second arm  130  with respect to the first arm  120 . However, with this arrangement, the bias that is applied by torsion spring  340  is applied directly to arms  120  and  130 , whereas, for spring  140 , the bias is applied through the rivet  150  and its connection to the first arm  120 . As seen in  FIG. 20 , for catch assembly  101  and release assembly  201 , the hook portion  341 H of the first leg  341  of torsion spring  340  may wrap around the first arm  120 , in proximity to its stop  125 , while the hook portion  342 H of the second leg  342  may wrap around the second arm  130 . When the first arm  120  and second arm  130  are extended by opening of the sash, the torsion spring is elastically deformed, and as seen in  FIG. 21 , the first and second legs  341  and  342  of the spring  340  being so deformed apply a biasing force to the arms  120  and  130 . Here again, once the release assembly  201  no longer has its hook secured within the opening  135  of the second arm, the spring  340  will bias the two arms to rotate toward each other until the side of the second arm contacts stop  125 , as seen in  FIG. 20 . 
     For release assembly  201 , the hook member used therein may take a slightly different shape, and a hook member  410 , which is shown in detail within  FIGS. 30-33 , may be used instead of hook  210 . Hook  410  may be formed similar to hook  210 , but may have a hook portion  410 C that is more rectangular in shape, and its return flange  414  may have a bent end flange  415  thereon, which may serve to more positively retain the hook in engagement with the switch member. The release assembly  201  may also use a base member  430  and a switch member  420 , with the features of each being shown in detail within  FIGS. 22-25 , and  FIGS. 26-29 , respectively. 
     The examples and descriptions provided merely illustrate a preferred embodiment of the present invention. Those skilled in the art and having the benefit of the present disclosure will appreciate that further embodiments may be implemented with various changes within the scope of the present invention. Other modifications, substitutions, omissions and changes may be made in the design, size, materials used or proportions, operating conditions, assembly sequence, or arrangement or positioning of elements and members of the preferred embodiment without departing from the spirit of this invention.