This invention relates to a combination sofa sleeper bed, and more particularly, to an improved sofa sleeper deck structure.
Sofa sleepers are well known in the prior art. Basically, a sofa sleeper includes a foldable bed frame which supports a mattress when the bed frame is extended to a generally flat, horizontal bed configuration. A sofa sleeper is adapted for use as a sofa when the bed frame is folded up into a collapsed storage configuration within the framework of the sofa to permit use of the structure as a seating surface.
A problem with sofa sleepers is that they offer little resistance or support when a person sits, reclines or rests on the unfolded sofa bed. This yield and effect is known in the bedding industry as "hammocking" and results in persons atop the mattress supported on the unfolded sofa bed feeling the underlying support members. As a result, sofa sleepers have been considered a compromise and a less satisfactory sleeping surface than a standard bed.
One prior solution to the problem of hammocking in sofa sleeper structures is disclosed in U.S. Pat. No. 2,878,490. The deck of the sofa sleeper in this patent includes a wire mesh or wire grid attached to the foldable bed frame. The wire grid either extends the full length of the foldable bed frame or a major portion thereof, the remainder being made from cloth. This wire grid or wire and cloth grid is connected with the sides of the foldable bed frame by a plurality of tension springs in order to maintain the grid in a taut and partially resilient posture when the frame is unfolded for use as a bed. However, the wire grid, or wire and cloth grid, even with the tension springs does not maintain the sofa sleeper deck in a sufficiently taut and resilient manner to avoid sagging of the unfolded sofa sleeper.
Another prior art solution to the problem of sag in a sofa sleeper deck is described in U.S. Pat. No. 4,584,727 which discloses a sofa sleeper deck wherein the deck is divided up into head, body, intermediate, and foot sections. The foot section is comprised of a plurality of sinuous wires. The remaining sections are constructed of plywood as either solid panels, individual slats, or pairs of slats. Although the plywood deck may solve the problem of hammocking to provide a resilient sleeping surface, a problem associated with a sofa sleeper deck of such construction is that the plywood panels are excessively rigid and therefore provide an uncomfortable seating surface when the deck is collapsed into the sofa. Furthermore, a sofa sleeper constructed with a plywood deck is extremely heavy, costly, and very difficult to move and transform to and between the sofa configuration and the sleeper configuration.
Sofa sleeper decks which merely include longitudinal slats, for example, of the type disclosed in U.S. Pat. No. 1,527,416, do provide a more lightweight deck construction. However, they do not provide a very rigid support structure for the mattress in the sleeper configuration. As a result, hammocking still occurs in sofa sleeper decks of this type.