Abstract:
The present invention relates to a positioning device for a backrest of a stroller, which can fix the backrest frame of the stroller on different positions to meet variety-resting needs. Especially, when the backrest frame is on a position undertaking larger loading, it secures the backrest from taking off or dropping down. The positioning device for a backrest of a stroller comprises a positioning seat mounted on a rear frame of the stroller and a wedging hook mounted on the backrest for engaging with the positioning seat. A safe shield is equipped on the positioning seat for securely maintaining the position between the wedging hook and the positioning seat to make the backrest firmly keep fixed position when an accidentally torsion force occurs.

Description:
BACKGROUND OF INVENTION 
     1. Field of Invention 
     The present invention relates generally to a positioning device for use in a backrest of a stroller which is adjustable in the angle of elevation and, more particularly, is well designed for undertaking additional torsion imposed on it and maintaining the predetermined position. 
     2. Related Art 
     A stroller is normally composed of a front frame, a rear frame, a handrail frame, a seat frame and a backrest. The conventional frames of a stroller are structured to have a foldable mechanism for convenience of carrying out and for the reduction of occupied space. Wheels are connected to the front and rear frames for easy moving. Soft pads are put on the seat frame and the backrest for more comfortable seating. The backrest of the stroller is generally one of two types, fixed or adjustable. The backrest in the fixed type is fixed on the seat frame and has only one declining angle after being assembled, while the adjustable type is pivoted on the seat frame and is adjustable in the declining angle. The angle between the seat frame and the backrest can be 180 degrees, that is, the backrest is in the same smooth plane with the seat frame for the baby to lie down, or 100 or 120 degrees for different lying posture. The point is that the adjustable backrest is always fixed to support the baby when it is moved to the desired position. 
     As taught in the U.S. Pat. No. 5,482,311, which disclosed a backrest adjusting device for a stroller which includes a slidable seat slidably mounted to each of the two limbs of a backrest frame member of the stroller. Each slidable seat includes a receptacle, a spring mounted in the receptacle, a first pin mounted above the spring and transversely passing through an associated limb of the backrest frame member, a stop piece mounted in the receptacle and located above the first pin thereby defining a lowermost position of the slidable seat, and s second pin projecting outward from an outer periphery thereof. A pull bar is mounted between the slidable seats. The second pin engage with sockets defined in a frame of the stroller when the backrest frame member is in a substantially upright position. The backrest frame member is pivotable to a substantially horizontal position when the second pin disengage from the socket upon actuation of the pull bar which causes upward movement of the slidable seats. 
     U.S. Pat. No. 5,447,323 disclosed another positioning device of backrest of a stroller which comprises a positioning plate securely mounted to each of two limbs of the backrest frame member of the stroller and has a pushing piece extending toward a front direction of the stroller and a flexible operative piece having a recess therein which faces the front direction of the stroller. The stroller has a pair of mounting seats for mounting the canopy frame member and the rear members thereof to the handle thereof. Each mounting seat has a peg thereon for releasably engaging with the recess of the associated flexible operative piece. 
     All the above-mentioned patents belong to the kind of positioning devices for a backrest of a stroller which have to do with the loading of a child imposed thereon when sitting on the stroller. They employ hooking devices which engage with the accompanying pegs downward or upward to complete the positioning action. 
     However, whatever positioning devices are used, they must be capable of firmly holding the position set and secure the child sitting thereon. In the case of aforesaid unsteadily vibration, the child makes not only a downward gravity force but also a lateral or tortional force. This will cause the positioning device to move from its predetermined position and cause the backrest to suddenly fall down, which can, in turn, injure the child. 
     The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results could be obtained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and detailed description of the preferred embodiment in addition to the scope of the invention as defined by the claims taken in conjunction with the accompanying drawings. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides mainly a positioning device for use in a backrest of a stroller which securely maintains the intended position. 
     In order to meet the object of the present invention, which comprises: a positioning seat mounted on the rear frame and a wedging hook mounted on the backrest for engaging with the positioning seat. A safe end is equipped on the positioning seat for securely maintaining the position between the wedging hook and the positioning seat to make the backrest firmly keep its position when an accidentally torsion force occurs. 
     These and other features of the present invention will become more fully apparent from the following description and dependent claims taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is illustrated by the following drawings in which: 
     FIG. 1 is a perspective view of the embodiment of the present invention. 
     FIG. 2 is a perspective view of the detailed structure of the present invention. 
     FIG. 3A is an enlarged perspective view of the present invention, depicting the positioning status of the positioning device. 
     FIG. 3B is an enlarged perspective view of the present invention, depicting another positioning status of the positioning device. 
     FIG. 3C is an enlarged perspective view of the present invention, depicting the other positioning status of the positioning device. 
     FIG. 3D is a sectional view of the present invention, depicting the positioning status of the positioning device. 
     FIG. 4 is a sectional view of the present invention, depicting the actuation status of the positioning device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The first embodiment of the present invention provides a positioning device for a backrest of a stroller. Referring to FIG. 1, the stroller  10  is mainly composed of a front frame  101 , a rear frame  102 , a handrail frame  103 , a seat frame  104  and a backrest frame  105 . Wheels  106  and  107  are connected to the front and rear frames  101  and  102  for moving easier. Soft pads  108  are placed on the seat frame  104  and the backrest frame  105  for more comfortable seating. The present invention aims at the improving the positioning function of the backrest frame  105 , so that the backrest frame  105  must be connected to an adequate place of the seat frame  104  by a movable junction in order to easily change the inclination angle thereof. 
     Referring to the FIG. 2, the positioning device  20  of the embodiment of the present invention is composed of a pair of positioning seats  201 , a pair of wedging hooks  202  and a pull bar  203 . 
     The positioning seat  201  is in an adequate place of the rear frame  102 . The positioning seat  201  comprises a mounting portion  2011  which is arc-shaped in its surface plane and firmly mounted on the limb of the rear frame  102 , a slide rim  2012  which is extended from the side face of the mounting portion  2011  and inclines a little and positioning recesses  2013  and  2014  which are located on both ends of the slide rim  2012  with their open faces upward. 
     The wedging hook  202  is mounted on an adequate place of the backrest frame  105  where the positioning seat  201  matches the wedging hook  202  when the backrest frame is in its moving interval. The wedging hook  201  is about the shape of ‘ν’, and a first holding tube  2021  and a second holding tube  2022  are connected to both ends thereof The first holding tube  2021  and the second holding tube  2022  are open on both ends for being fitted through by the limb of the backrest frame  105 . The first holding tube  2021  is fixed on the backrest frame  105  while the second holding tube  2022  is not fixed. Therefore, the second holding tube  2022  connected to one end of the ‘ν’ shaped wedging hook  202  can move a little toward the first holding tube  2021  by applying an external force. A first extend portion  2023  and a second extend portion  2024  are extended outward from the first holding tube  2021  and the second holding tube  2022 , respectively. A first perforation  2025  and a second perforation  2026  are located on the first holding tube  2021  and the second holding tube  2022 , respectively. A positioning piece  2027  extends outward from side face of the second holding tube  2220  and is located on the place where the positioning piece  2027  properly matches the slide rim  2012  of the positioning seat  201 . Moreover, the positioning piece  2027  could have a wedging recess  2028 . 
     The pull bar  203  has the shape of ‘U’, which passes through the first and second perforations  2025  and  2026  and has its one end fixed on the second perforation  2026 . When the pull bar  203  is pulled, the second holding tube  2022  slightly moves toward the first holding tube  2021 . 
     Referring to FIGS. 3A,  3 B and  3 C, the backrest frame  105  of the stroller  10  can pivot on the joint  1041  intersecting of the backrest frame  105  and the seat frame  104  in a variety of declining angle. In FIG. 3A, for example, the declining angle between the backrest frame  105  and the seat frame  104  is about 180 degree, that is, the backrest frame  105  is lying down horizontally, which is named the backrest frame  105  is inclining to the extent of resting, which is named the second position. Referring to FIG. 3C, the declining angle between the backrest frame  105  and the seat frame  104  is about 100 degree, that is, the backrest frame  105  is inclining to another resting position, which is named the third position. When the backrest frame  105  is on the first position, the position can be kept by applying a link bar or a wire cable, not figured out. Accordingly, the second and the third positions of the backrest frame  105  are kept by the positioning device  20 , wherein the second holding tube  2022  of the wedging hook  202  right matches the positioning seat  201  when the backrest frame  105  is in a moving interval and the positioning piece  2027  of the second holding tube  2022  moves along the slide rim  2012  of the positioning seat  201 . 
     When moving in the interval of angle from 100 to 120 degree between the backrest frame  105  and the seat frame  104 , the positioning piece  2027  of the wedging hook  202  moves along the slide rim  2012  of the positioning seat  201  until the backrest frame  105  goes to the second position. The loading force, then, pushes the positioning piece  2027  of the wedging hook  202  to the positioning recess  2013  of the positioning seat  201 . This causes the backrest frame  105  to be kept on the second position. In FIG. 4, when moving the backrest frame  105  to the third position, the pull bar  203  is pulled upward to make the second holding tube  2022  slightly moving toward the first holding tube  2021 . At this moment, the positioning piece  2027  of the wedging hook  202  disengages from the positioning recess  2013  of the positioning seat  201  and still moves along the slide rim  2012  until falling into the positioning recess  2014 . The backrest frame  105  then kept on the third position. Accordingly, if the backrest frame  105  is to be moved from the third position, we can also pull the pull bar  203  upward to disengage the positioning piece  2027  of the wedging hook  202  from the positioning recess  2014  of the positioning seat  201 . 
     The loading force, gravity, pulls the positioning piece  2027  downward to fall into the positioning recesses  2013  and  2014  vertically and keeps the positioning piece  2027  inside the positioning recesses  2013  and  2014 . Furthermore, there are safe shields  2015  and  2016  extending from side faces of the positioning recesses  2013  and  2014  separately. They secure the positioning piece  2027  against escaping from the positioning recesses  2013  and  2014  when the stroller  10  is imposed on a lateral force or torsion. The wedging recess  2028  of the positioning piece  2027  does a further effect of hooking on to safe shield  2015  or  2016 , as in FIG.  3 D. This makes the using of the stroller  10  safer. 
     As to the manner of usage and operation of the present invention, the same should be apparent from the above description. Accordingly, no further discussion relating the manner of usage and operation will be provided. 
     With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. 
     Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not described to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be restored to, falling within the scope of the invention. 
     EFFECTS OF THE INVENTION 
     According to the embodiments of the present invention, the positioning device for a backrest of a stroller. it not only fixes the declining angle of the backrest frame by the positioning device but also resists the lateral force or torsion imposed on the stroller through the safe shields of the positioning recesses. Consequently, it firmly positions the backrest frame in a desired position and secures the child taking the stroller against danger. 
     Numerous variations and modifications will suggest themselves to persons skilled in the arts, other than those already described, without departing the basic inventive concepts. Although the present invention has been described with respect to typical preferred embodiments thereof, it should be understood that the present inventions is not limited to these embodiments, and various changes or modifications may be made without departing from the scope of the present invention as defined by the appended claims.