I found this through Dezeen – apparently you extend the front bar and drop the upright cushion down to convert from sofa to bed…

My Two Bits:

If you design the cushions correctly you ought to be able to switch between sofa and couch without needing to extend the frame. Simply make sure the skinny cushions are significantly wider than they are thick and that the upright cushion is the same thickness as the width of the skinny ones. When converted to a bed, the upright cushion is rotated to take up more room while the skinny cushions are rotated to take up less. Might only work for a twin size without the couch being obscenely deep; however, it removes the need for any moving frames – just rotate the cushions!