Portable booster seat

1. In a foldable seat assembly having an outer shell including a back support, sidewalls and a bottom member, the combination comprising:

a cushioned seat member having at least one hinged support panel between said sidewalls and spanning a width of an underside of said seat member, said cushioned seat member resting upon said hinged support panel when in an unfolded, use position;

an upright back support to which said cushioned seat member hingedly connected by a hinge member to said upright back support; and

foldable sidewalls extending forwardly from and hingedly connected to said back support along opposite sides of said seat member.

2. The seat assembly according to claim 1 wherein said hinged support member panel includes a plurality of support panels hingedly connected to said seat member.

3. The seat assembly according to claim 2 wherein said support panels are movable between a folded position and an unfolded position extending perpendicular to said seat member.

4. The seat assembly according to claim 1 wherein said back support includes means for surrounding said seat member.

5. The seat assembly according to claim 4 wherein said surrounding means includes said sidewalls, a front wall and a bottom panel.

6. The seat assembly according to claim 4 wherein said surrounding means is dimensioned to accommodate said seat member.

7. The seat assembly according to claim 1 wherein said hinge member connects an upper rear portion of said seat member to said upright back support.

8. A portable infant booster seat comprising:

an outer shell having an upright back support, foldable sidewalls extending forwardly from and hingedly attached to opposite sides of said back support, and a flexible front wall;

a cushioned seat member including means for hingedly attaching said seat member to said back support;

means for supporting said seat member in an elevated position including a support member positioned between said front wall and said back support, said support member including at least one rigid platform and at least one hinged member hingedly connected to said platform, said at least one hinged member hingedly attached to an underside of seat member, said cushioned seat member resting upon said support member when in an unfolded, use position; and

means for limiting movement of said seat member between a horizontal position and an upwardly extending position into flush engagement with said back support.

9. The booster seat according to claim 8 wherein said sidewalls and said front wall include rigidifying members.

10. The booster seat according to claim 8 wherein said bottom member extends between lower edges of said sidewalls and said front wall.

11. The booster seat according to claim 8 wherein said seat member is upwardly extendible into parallel alignment with said back support.

12. The booster seat according to claim 8 wherein said outer shell is dimensioned to accommodate said seat member.

13. The booster seat according to claim 8 wherein said limiting means includes said hinging means and said rigid platform.

14. A collapsible booster seat assembly comprising:

an outer shell having foldable sidewall support members, a rigid back support, a front wall and a bottom member;

a cushioned seat member having a hinged means for supporting said seat member in an elevated position, wherein said hinged support means includes dual platform members, said dual platform members including an upper platform attached to an underside of said cushioned seat member and a lower platform spaced apart from said upper platform, each said platform members having a front and a mid-section panel member inserted therebetween, wherein said front and mid-section panel members are hinged at opposite ends to said platform members;

said cushioned seat member resting upon said hinged support means when in an unfolded, use position; and

a hinge member hingedly connecting said seat member to said back support.

15. The booster seat according to claim 14 wherein said sidewalls are connected along opposite side edges of said bottom member.

16. The booster seat according to claim 14 wherein said outer shell is dimensioned to accommodate said seat member.

17. The booster seat according to claim 14 wherein said panel members are movable between a folded position extending parallel to said platform members and an unfolded position extending perpendicular to said platform members.

18. A method of supporting an infant in a booster seat assembly, said seat assembly having an outer shell comprising a rigid, upright back support, foldable sidewalls hingedly connected to said back support, a cushioned seat member having at least one hinged support panel spanning an underside width of said seat member, said hinged support panel located between upper and lower platforms of said cushioned seat member, said hinged support panel hingedly connected between an underside of said upper platform and an upper surface of said lower platform, said seat member hingedly connected to said back support, the method comprising the steps of:

unfolding said sidewalls from a position overlapping one another and said seat member to a position extending along opposite sides of said seat member;

adjusting said front member to form a seat housing;

lowering said seat member into a horizontal position between and supported by said sidewalls;

positioning said support panel in relation to said seat member to provide elevation to said seat member by resting said cushioned seat member on said support panel;

seating an infant on said seat member; and

securing the infant to said seat member with child restraints.

19. The method according to claim 18 wherein said seat member support panel is defined by rigid front and mid-center panels.