Abstract:
A locking device for baby strollers is described which is automatically engaged and disengaged based simply on the presence or absence of a human hand on the stroller handle. If there is no hand on the stroller, the lock is automatically engaged, and if a hand is present on the handle, the lock is automatically disengaged.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to baby strollers and the like and more particularly to stroller locking devices that prevent a baby stroller from rolling along the surface. 
       SUMMARY OF THE INVENTION 
       [0002]    It is well known within the art relating to baby strollers that it is desirous to be able to engage and disengage a locking device that prevents the baby stroller from rolling away in an uncontrolled fashion. Almost exclusively, these locking mechanisms require them to be manually engaged and disengaged by the user. This has resulted in numerous cases of runaway baby strollers when the user forgets to engage the locking device and the stroller and the baby roll away. Typical locking devices will engage with either one or both rear wheels of the stroller and prevent the stroller wheel from rolling. However, to date, these locking devices require that they be manually engaged by the user, typically by pressing on a locking lever with a foot to engage and disengage the locking device. More recently, some strollers also include a hand activated locking mechanism that requires a grip located on the stroller handle to be squeezed in order to release the locking device. 
         [0003]    There therefore is a need for a locking mechanism that will automatically engage whenever a user&#39;s hand is not touching the handle of the stroller and automatically disengages when a user touches the handle of the stroller. The mechanism must be powered through the use of an on board replaceable or rechargeable battery. The mechanism preferably should be robust enough to ensure it safely prevents the stroller from rolling away uncontrollably and quickly engages and disengages in response to the touch of the human hand to the handle of the stroller. 
       OBJECTS OF THE INVENTION 
       [0004]    In addition, other objects of the invention are to provide a highly reliable, easy to use automatic locking device for baby strollers that prevents injury to babies as a result of a runaway stroller due to the user forgetting to lock the stroller. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a side view in accordance with an embodiment of the invention; 
           [0006]      FIG. 2  is a schematic view of the stroller locking device in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0007]    Referring first to  FIG. 1 , which depicts a baby stroller  10  in accordance with an embodiment of the invention. As well known in the art, the baby stroller  10  is comprised of four wheels  12  (note that some strollers have only three wheels) that roll along the surface, a frame structure  14  is configured to hold a seating area  16 . The seating area  16  is configured to safely receive and retain a baby of various sizes. Typically a handle frame  18  is provided that extends upwardly so that a user may control the stroller  10  from a rear position as the stroller  10  is pushed from behind. 
         [0008]    In a preferred embodiment, disposed on the handle frame  18  may be a touch plate  20  that is in communication with an electrical circuit  22  that is configured to sense the presence or absence of a human hand. The touch plate  20  may be disposed below the surface or integral to the surface of the handle frame  18 . In the preferred embodiment, the touch plate  20  may be an electrically conductive material that is embedded below the surface of the elongated handle frame  18 . 
         [0009]    As mentioned above, the touch sensor  20  is connected to an electronic circuit  22  that is configured to control an actuator  24 . The actuator  24  may be a solenoid or a servo or other type of mechanical actuator that is configured to be selectably positioned between and extend or retracted position in response to a signal from the electronic circuit  22 . A battery  26  powers the locking system, and preferably the battery  26  is easily replaceable and/or rechargeable. 
         [0010]    Referring now to  FIG. 2 , which depicts a simplified schematic of the electronic circuit  22  and devices associated with an embodiment of the invention, the operation of the invention will now be described in more detail. 
         [0011]    As mentioned previously, the touch plate  20  is in communication with the electronic circuit  22  such that the actuator  24  extends to a locking position when a user is no longer touching the handle  18  or the actuator  24  will retract to an unlocked position when a user touches the handle  18 . The exact configuration of the actuator  24  and the associated mechanical interface to the wheel  12  may take on many variations, all such variations are fully contemplated by this disclosure. The stroller  10  will be in a locked and safe configuration when no one is holding the handle  18 , and will be in an unlocked position when the user&#39;s hand is on the stroller&#39;s handle. 
         [0012]    In the preferred embodiment, the circuit  22  and the actuator  24  should be configured to use very little electrical power so that the battery will last a long time, for example a year or two. This can be accomplished by only using battery power during the extension and retraction of the actuator  24 . Therefore it may be preferable to have the actuator  24  mechanically held in the extended or retracted position without drawing any current from the battery  26 . The actuator  24  may be electrically extended or retracted by altering the polarity of the voltage applied to the actuator  24 . 
         [0013]    In a preferred embodiment, and without limiting the variations possible, the actuator  24  extends a shaft  30  to a locked position such that it engages with a single pocket  28  that is formed in one of the wheels  12  of the stroller  10 . A plurality of evenly spaced pockets  28  may be provided circumferentially along the wheel  12  such that the shaft  30  will engage a pocket no matter the orientation of the wheel  12 . A spring  32  may be provided along the shaft  30  so that the shaft  30  is forced into a pocket  28  and held there under the spring&#39;s force. The spring  32  will help to ensure the shaft  30  is fully seated in a pocket  28  which will prevent the wheel  12  from rotating. 
         [0014]    When the user touches the handle  18 , the touch plate  20  in combination with the electronic circuit  22  will communicate with the actuator  24  and retract the shaft  30  to an unlocked position which will allow the wheel  12  to rotate freely. The shaft  30  may be held in an unlocked position by a mechanical detent (not shown) and therefore requires no electrical power to stay in the unlocked position. 
         [0015]    Although an exemplary embodiment of the invention has been shown and described, many changes, modifications, and substitutions may be made by one having ordinary skill in the art without necessarily departing from the spirit and scope of this invention. For example, in the embodiment described, a single shaft is employed to engage with a pocket located on wheel of the stroller. The exact configuration of this locking mechanism could be easily modified and adapted to provide the same functionality. All such variations and modifications are fully contemplated by this invention.