Lie back buggy

A chair frame of elongate rigid members which are inter-pivoted and foldable into a compact bundle in which the rigid members extend substantially parallel to each other, the chair frame comprising:

• (a) two base members which are pivotally interconnected to form a laterally collapsible X-frame in which the opposite ends of the two base members provide front and back corners of the X-frame;
• (b) two back members which are disposed on coplanar axes and respectively extend upwardly from pivotal connections at the back corner of the X-frame;
• (c) two lower brace members respectively pivoted, at their lower ends, to the front corners of the X-frame;
• (d) two upper brace members respectively pivoted, at their upper ends, to the upper ends of the back members;
• (e) two knuckle joints respectively connecting the two lower brace members to the two upper brace members so as to prevent folding of the back members towards the X-frame when the chair frame is extended with the lower brace members respectively extending substantially colinearly with the upper brace members and the front or rear corners of the X-frame are held apart, but to allow the knuckle joints to move towards the back corners of the X-frame, thus permitting folding of the back members towards the X-frame when the back corners of the X-frame are allowed to move towards each other;
• (f) two seat support members respectively pivoted to the chair frame at or adjacent the back corners of the X-frame and respectively pivoted to the lower brace members between the knuckle joints and the front corners of the X-frame;
• (g) two upwardly extending back rest members which are disposed on coplanar axes and form part of a laterally collapsible back rest, respectively supported on the two seat support members and respectively mounted for pivotal movement so that the upper ends of the back rest members are movable between upper and lower positions;
• (h) a laterally collapsible bracing frame which can be locked to hold the back corners of the X-frame apart and is located adjacent the X-frame so that the back rest members can be moved between their upper and lower positions without being obstructed by the collapsible bracing frame;
• (i) the laterally collapsible bracing frame comprising two locking struts interconnected by a pivot and respectively pivotally connected at opposite ends to the back corners of the X-frame, two link members, each such link member being supported on a respective first pivot at one end of the link at a fixed location on a respective back member, the fixed location being remote from the respective back corner of the X-frame and each such link member being pivotally connected, remote from the first pivot of the link member, to the pivotal connection of the two locking struts by a common member which forms with a locking strut, a link member and a back member a parallelogram linkage;
• (j) the common member forming a slide arranged to limit movement of the parallelogram linkage, and pivotally connected to one end of two obliquely disposed supporting members having their other ends connected to respective back corners of the X-frame.