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FIELD OF THE INVENTION 
   The present invention relates generally to operators, and more particularly, to projection window operators. 
   BACKGROUND OF THE INVENTION 
   Casement, double-hung, sliding, and other windows are common and generally known. These windows and their associated operators provide ventilation and interior/exterior access by generally displacing a window sash relative to a surrounding frame structure through slidable or pivotal movement. In some applications, however, such displacement is undesirable. For example, displacement of a sash relative to a surrounding frame can be esthetically displeasing from the exterior, particularly on large buildings with many windows. A casement window, in which the window typically pivots outward relative to the frame, can be impractical or dangerous in areas of high wind. 
   Projection, or stand-out, windows are also known and can be used where it is desired to minimize the visual impact of open windows relative to the rest of a structure, or where it is impractical or infeasible to use the windows described above. A projection window generally provides a horizontal displacement of the sash relative to the surrounding frame, thereby providing a trickle ventilation around the entire window. 
   For example, U.S. Pat. Nos. 497,296 and 531,244 disclose early projection-type windows. These windows were suited for ventilating railway passenger cars, among other applications. 
   U.S. Pat. No. 2,374,618 discloses a sash movably supported on a window frame at each of opposite vertical sides thereof by a link arrangement comprising a long bar and short bars, the two latter respectively lying at opposite sides of the long bar. The construction described and depicted permits the sash adjustably to be moved bodily away from the window frame and into various positions. 
   A stand-out window opening mechanism is described in U.S. Pat. No. 4,866,882. The window opening mechanism moves the entire window sash outwardly from the window frame in a plane parallel to the plane of the frame. The mechanism for accomplishing this includes a pair of pivoted L-shaped lever arms on each side of the window. The short legs of these lever arms are substantially shorter than the long legs, and the ends of the short legs are pivotally attached to the window frame relatively close together. An operating mechanism is provided for moving the elbows of the lever arms toward and away from one another, and the ends of the long legs of the arms are pivotally connected at spaced apart points on the window sash. As the elbows of the levers on both sides are moved toward one another, the window sash is pulled toward the frame. When the elbows are moved away from one another, the pivoting action of the lever arms causes the window sash to be moved outwardly from the frame to provide a “stand-out” opening of the window. 
   U.S. Pat. No. 6,070,637 discloses a horizontally openable window. The window comprises a screen-like enclosure between the window casement and the window frame that limits the amount of moisture or dust that can enter through the window when in an open position. 
   Projection windows such as those identified above that are presently known include complex mechanisms for operating the window and supporting the sash in both extended and retracted positions. These mechanisms can limit the applications of projection windows because they occupy more space and require a deeper window frame. Further, in some applications it may still be desired to operate a projection window like a casement window, opening and closing only one vertical side of the window on a pivot relative to the frame, or to similarly pivotally open and close only one horizontal side. 
   For the foregoing reasons, there is a need for a projection window operator that is compact and secure. There is also a need for a projection window operator that provides for selectable opening and closing of the window in various other configurations. 
   SUMMARY OF INVENTION 
   The present invention is directed to a window operator that is particularly suitable for use with projection-type windows. In one embodiment, the projection window operator includes a base, a cam, a stud, an arm, a cover, a roller, a rivet, and a roller rivet, in operable communication to horizontally project a window sash relative to a vertical plane of a window when assembled. The operator is mounted to a window frame via the base and to a window sash via a sash bracket. In operation, the operator is actuated by the cam between a first position in which the window is closed and a second position in which the window is open. In the first position, the cam is raised relative to the base and cover and the arm is retracted, holding the window closed. In the second position, the cam is lowered relative to the base and cover and the arm is extended, holding the window in an open position where the sash is horizontally projected relative to the vertical plane of the frame. 
   In one embodiment, at least two operators are installed on a window. For stability and support, at least one operator is installed on each of opposing vertical sides of the window. In a further embodiment, at least one operator is installed on each of opposing horizontal sides of the window. In a yet further embodiment, four operators are installed on a window, with two operators installed on each of opposing vertical sides of the window. The two operators on each side can be connected for simultaneous actuation. In one embodiment, all of the operators installed on a window are connected for simultaneous actuation. 
   In a further embodiment, selective ventilation is enabled by the operator. A configuration having two operators installed on opposing vertical sides of a window provides selective and independent actuation and projection of each vertical side. The operators located on a first vertical side of the window can be actuated simultaneously to open only that side of the window while the second vertical side is left closed or subsequently opened in the same manner as the first vertical side. 
   The above summary is not intended to describe each illustrated embodiment or every implementation of the invention. The figures and the detailed description that follow more particularly exemplify these embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which: 
       FIG. 1  is an exploded assembly view of a portion of a projection window operator in accordance with the present invention; 
       FIG. 2  is a perspective view of an embodiment of a projection window operator according to the invention depicting the operator and window in a closed position; 
       FIG. 3  is a cross-sectional end view of the projection window operator of  FIG. 2  depicting the operator and window in a closed position; 
       FIG. 4  is a perspective view of the projection window operator of  FIG. 2  depicting the operator and window in an open position; 
       FIG. 5  is a cross-sectional end view of the projection window operator of  FIG. 2  depicting the operator and window in an open position; 
       FIG. 6  is a perspective view of the base of the projection window operator depicted in  FIG. 1 ; 
       FIG. 7  is a plan view of the cam of the projection window operator depicted in  FIG. 1 ; 
       FIG. 8A  is a side view of the cam follower of the projection window operator depicted in  FIG. 1 ; 
       FIG. 8B  is an end view of the cam follower of the projection window operator depicted in  FIG. 1 ; 
       FIG. 9  is a perspective view of the arm of the projection window operator depicted in  FIG. 1 ; 
       FIG. 10  is a perspective view of the cover of the projection window operator depicted in  FIG. 1 ; 
       FIG. 11A  is a top view of the roller of the projection window operator depicted in  FIG. 1 ; 
       FIG. 11B  is a side sectional view of the roller depicted in  FIG. 11A  taken at section  11 B- 11 B; 
       FIG. 12A  is a side view of the rivet of the projection window operator depicted in  FIG. 1 ; 
       FIG. 12B  is a top view of the rivet of the projection window operator depicted in  FIG. 1 ; 
       FIG. 13A  is a side view of the roller rivet of the projection window operator depicted in  FIG. 1 ; 
       FIG. 13B  is a top view of the roller rivet of the projection window operator depicted in  FIG. 1 ; 
       FIG. 14  is a perspective view of the sash bracket of an embodiment of a projection window operator according to the present invention; 
       FIG. 15A  is a top view of a tie bar of an embodiment of a projection window operator according to the present invention; and 
       FIG. 15B  is a side view of the tie bar of  FIG. 15A . 
   

   While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in more detail herein. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described, but the should be understood to encompass all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
   DETAILED DESCRIPTION OF THE INVENTION 
   The projection window operator of the invention as disclosed herein provides a hardware system operable to horizontally project a window relative to the vertical plane of a surrounding frame. The operator is also adaptable for use with various window and ventilation configurations, for example a horizontally positioned window, vent, or skylight. The invention can be more readily understood by reference to  FIGS. 1-15B  and the following description. While the invention is not necessarily limited to such an application, the invention will be better appreciated using a discussion of representative embodiments as shown and described herein. 
   Referring to  FIG. 1 , a projection window operator  10  in accordance with one embodiment of the present invention generally includes base  20 , cam  40 , cam follower  60 , arm  70 , cover  80 , roller  90 , roller rivet  100 , and rivet  110  in operable communication to horizontally project a window sash  140  relative to a vertical plane of the window  150  when assembled. Operator  10  is mounted to a window frame  160  or other surrounding structure via base  20  and to the window sash  140  via a window sash interface in the form of sash bracket  120  ( FIG. 14 ). As depicted in  FIGS. 2-5 , operator  10  is actuated by cam  40  between a first position in which the window  150  is closed, as shown in  FIGS. 2 and 3 , and a second position in which the window  150  is open, as shown in  FIGS. 4 and 5 . In the first position, cam  40  is raised relative to base  20  and cover  80  and arm  70  is retracted, holding the window closed as depicted in  FIG. 2 . In the second position, cam  40  is lowered relative to base  20  and cover  80  and arm  70  is extended, holding the window in an open position where the sash is horizontally projected relative to the vertical plane of the frame. 
   The various components of operator  10  will now be described in more detail. The components described herein may be made from any and all suitable materials, such as plastics, metals, alloys, or any combination thereof, and scaled as appropriate for a desired application, so long as the functioning aspects of the operator and its components are not compromised. 
   Referring to  FIG. 6 , base  20  generally includes main portion  22 , fastener holes  26 , and raised side portions  28  defining channel  29 . Fastener holes  26  are formed to receive fasteners, such as screws (not shown), to secure operator  10  to a window frame. As depicted in the embodiment of  FIG. 6 , a single fastener hole  26  is located on each of two tab portions  24  positioned on opposing longitudinal ends of main portion  22  of base  20 , although in other embodiments the fastener holes  26  can be located on main portion  22  of base  20  or on tabs  24  located elsewhere on main portion  22  of base  20 . Raised side portions  28  of base  20  are formed so as to interlock with cover  80  ( FIG. 10 ) and define channel  29 . In one embodiment, side portions  28  include a plurality of teeth  30  positioned so as to be received by and interlock with apertures on cover  80 . Other means, for example tabs or pegs, can be used in place of teeth  30  to interlock with corresponding apertures on cover  80 . When operator  10  is assembled, base  20  and cover  80  interlock to substantially enclose cam  40 , arm  70 , and other components, with the longitudinal ends substantially open to permit actuation of cam  40  between the first position and the second position and corresponding pivotal movement of arm  70 . 
     FIG. 7  depicts cam  40  and  FIGS. 8A and 8B  depict cam follower  60 . Cam  40  is slidably disposed in channel  29  of base  20  and generally includes body portion  41  with a generally s-shaped cam slot  42  defined therein to receive and guide first portion  62  of cam follower  60 . Second portion  64  of cam follower  60  is fixed to arm  70  as further described hereinbelow. Cam slot  42  is generally angled with respect to a longitudinal axis of cam  40 , extending from a first slot end  48  proximate first edge  50  and corner of cam  40  to a second slot end  44  near the longitudinal center and proximate a second opposing edge  46  of cam  40 . The first and second slot ends  48  and  44  are formed at an angle α to the central portion of cam slot  42 , and generally parallel with the longitudinal axis of cam  40  such that the slot ends  44  and  48  hold cam follower  60  at the first slot end  48  when cam  40  is in the first position relative to base  20  ( FIG. 2 ) and the window is closed, and at the second slot end  44  when the cam is in the second position relative the base  20  ( FIG. 4 ) and the window is open. In one embodiment, angle α is 35 degrees. 
   Arm  70  is depicted in  FIG. 9 . Arm  70  generally includes first portion  66  and second portion  68  positioned at an angle with each other forming an elbow  79 . Arm  70  further has a plurality of apertures  72 ,  74 ,  76 ,  78  defined therein. First aperture  72  is defined proximate the distal end  73  of first portion  66  of arm  70 , and receives fastener  121  to rotatably couple arm  70  to sash bracket  120  ( FIG. 14 ). Although an angled configuration for arm  70  is depicted, any other configuration and connection of arm  70  with cam  40  and window sash interface  120 , including a straight arm  70 , that enables a projecting motion of window sash  140  from window frame  160  is also contemplated as being within the scope of the present invention. 
   Second aperture  74 , defined substantially in the middle of second portion  68  of arm  70  and proximate third aperture  76 , receives roller rivet  100  to rotatably and slidably couple arm  70  with cover  80  via roller  90 . Roller  90  is depicted in  FIGS. 11A and 11B  and roller rivet  100  in  FIGS. 12A and 12B . Roller  90  generally includes lip portion  92  and base portion  94 , wherein the radius of lip portion  92  is larger than that of base portion  94  to retain roller  90  in second aperture  82 . Roller rivet  100  extends through central aperture  96  in roller  90  to third aperture  76  of arm  70 , where chamfer angle Φ of central aperture  96  through lip portion  92  of roller  90  corresponds to an angle a of roller rivet  100 . In one embodiment, angles Φ and a are 45 degrees. As alternatives to roller  90  and roller rivet  100 , a wide variety of other arrangements for coupling arm  70  with cover  90  are contemplated within the scope of the invention. For example, roller  90  and roller rivet  100  may be replaced by a fastener without a roller fixed within second aperture  74  of arm  70  or with an integral projection of arm  70 , either of these being slidably received in slot  82  of cover  80 . 
   Second portion  64  of cam follower  60  is fixed within third aperture  76  of arm  70  so that cam follower  60  projects outwardly from arm  70 . It will be appreciated that as an alternative, cam follower  60  may be an integral projection of arm  70 . 
   Rivet  110  is received in fourth aperture  78  to couple arm  70  to cover  80 . It will be appreciated that arm  70  could be coupled to cover  80  via any other suitable structure slidable in slot  84  of cover  80 , such as for example an integral projection formed on arm  70 . 
   When cam  40  is actuated between the first position and second position, arm  70  is actuated between a first retracted position ( FIG. 2 ) and a second extended position ( FIG. 4 ), extending and retracting sash bracket  120  ( FIG. 14 ) coupled to the window sash and thereby opening and closing the window. 
   Cover  80  is depicted in  FIG. 10  and includes arm guide structures in the form of non-parallel slots  82  and  84 . Slot  82  is defined proximate a first longitudinal end of cover  80  and at a slight angle so as to receive roller  90 . Slot  84  is defined proximate to and extending perpendicularly from the opposing longitudinal end of cover  80 . Slot  84  receives rivet  110  to define the motion of arm  70  when cam  40  is actuated between the first position and the second position. Slots  82  and  84  are configured such that actuating cam  40  extends arm  70  to displace sash bracket  120 , depicted in  FIG. 14 , generally perpendicularly relative to the plane of the window. Cover  80  further includes apertures  86  configured to interlock with teeth  30 , or other interlocking means, and couple cover  80  to base  20  as described above. Although depicted as a separate component in the depicted embodiments, in other embodiments of the invention (not depicted), cover  80  may be integrally formed with base  20 . Moreover, in other alternative embodiments (not depicted) cover  80  may be entirely omitted. In these embodiments, arm  70  may directly coupled to base  20  at a single attachment point, and cam  40  actuates arm  70  as cam  40  is moved as before. 
   When the window is closed, first portion  62  of cam follower  60  is positioned in first slot end  48  of cam slot  42  to hold arm  70  in a retracted position, locking the window in a closed position. As cam  40  slides between the first position and second position to open or close the window, cam follower  60  slides within cam slot  42  as rivet  110  slides within cover slot  84  and roller  90  and roller rivet  100  interact with cover slot  82  to extend or retract arm  70  and sash bracket  120  and horizontally to displace the window sash relative to the vertical plane of the window frame. Moving the window sash perpendicularly with no parallel motion component relative to the plane of the window frame minimizes the effort required to open and close the window because the window is neither raised nor lowered. When the window is open, cam follower  60  is positioned in second slot end  44  of cam slot  42  to hold arm  70  in an extended position, locking the window in the open position. Cam  40  is also operably coupled to tie bars  130 , shown in  FIGS. 15A and 15B , via apertures  44  or other means, where tie bars  130  are operable to actuate cam  40  between the first and second positions. 
   To provide stability, at least three operators  10  will generally be installed on a window, with each located on a different side of the window for adequate support. Alternatively, two operators  10  could be located on a first side of the window and a third operator  10  could be located on a second, opposite side. Preferably, four operators  10  will be installed on a window, with two operators  10  located on opposing vertical sides of the window, or on opposing horizontal sides of the window. 
   In an installation having two operators  10  installed on each vertical side of the window, tie bars  130  can operably interconnect the first operator  10  to the second operator  10  located on the same vertical side of a window such that the two operators  10  are actuated in unison. In one embodiment, all of the operators  10  on a window are connected so as to be actuated and to operate in unison. 
   Selective ventilation can also be enabled by the invention. A configuration having two operators  10  mounted on opposing vertical sides of a window further provides selective and independent actuation and projection of each vertical side. The operators  10  located on a first vertical side of the window can be actuated simultaneously to open only that side of the window while the second vertical side is left closed or subsequently opened in the same manner as the first vertical side. Operation in this manner is possible with limited compliance between the sash brackets  120  and the arms  70  on each operator  10 , as the plane of the window does not remain perpendicular to the planes of the arms  70 . Similarly, operators  10  can be mounted on opposing horizontal sides of a window to provide selective ventilation along either the top or bottom edge. 
   Although the present invention has been described in considerable detail, it will be appreciated that additional advantages and modifications will be readily apparent to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Summary:
A projection window operator providing horizontal displacement of a window relative to a vertical plane of the frame of the window. With at least one projection window operator installed on each of opposing sides of the window, the window can be actuated between a first closed position and second open position in which a trickle ventilation is provided around the window. The projection window operators installed on the window can be interconnected for simultaneous actuation, or actuated individually, providing selective ventilation on either side.