This invention generally relates to a folding chair and, more particularly, to a folding chair having a capped plunger joint to prevent potential damage to the legs of the chair and a push button safety lock for safely supporting the frame of the chair in a working position. 
Folding chairs are well known in the art to provide for easier displacement and compact storage during non-use.  Folding chairs typically consist of two sets of legs, front and rear, that are pivotally attached.  A seat is also pivotally attached to the legs such that when the legs are separated, the seat is horizontal to the ground and can thus support a user.  Typically, the front set of legs have a back rest that extends therebetween. 
Conventional folding chairs typically have a linkage that extends between the front and rear sets of legs above the seat such that pivoting the seat to a vertical position pivots the rear set of legs into parallel arrangement with the front set of legs and seat in the folded position.  The linkage is typically a thin rectangular cross-sectional bar of metal, that when brought toward alignment with the front and rear sets of legs, creates a crushing or cutting point for fingers and permits direct impact between the metal surfaces of the leg assemblies and/or the linkages.  The potential for injury is especially true when the folding chair is sized for use by a child.  Children typically do not have sufficient experience with using folding chairs and do not know or appreciate the finger danger at the joints when collapsing the chair. 
As a result, folding chairs have been developed to include a plunger in the rear set of legs, thereby eliminating the potentially dangerous linkage.  However, in order to prevent the rear set of legs from contacting and damaging the joints connecting the rear and front sets of legs a stepped shaft has been used or a specially shaped joint that extends past the pivot point to engage with the rear legs.  Such a configuration requires expensive machined parts or a molded joint that is more likely to break. 
It would therefore be desirable to provide a folding chair with an inexpensive and durable plunger joint that prevents the rear set of legs from contacting and damaging the joints.  It is further desirable that the folding chair have a safety mechanism that prevents the chair from collapsing unintentionally.