Innovations in convertible bedding

In an era of shrinking living spaces and vanishing bedrooms, furniture manufacturers are rising to the demand for more and different dual sleep arrangements.

Entirely new mechanisms, introduced this past year, mean that people now have different options when they go to purchase a piece of furniture that conceals a sleeper as well. A convertible sofa? Of course, but the new mechanisms enable many of them to sit lower and to be sleeker and more low-slung in silhouette.

The most significant change, however, is that you can now choose a coffee or sofa table that converts into a bed, a convertible credenza, a convertible buffet, a convertible ottoman, a convertible chest, or a convertible wall system cabinet. Mattresses in these hidden sleeping units range in width from 32 to 68 inches.

In a year or two there will probably be convertible-other-things, as people get the message that, with these innovative pieces, they can tuck in an overnight guest almost anywhere in the house. This is a real consideration, not only because of the at-home space crunch, but because of rising hotel rates that impel people to put up friends and family when and where they can.

The new trifold mechanism (which folds a thinner mattress three times instead of the usual twice) is the space-saving device that has brought so much excitement and change to the dual-sleep field. It eliminates the need for a back cavity in sofas.

As made by the Super Sagless Corporation of Tupelo, Miss., the unit comes with a 78-inch-long mattress, which is six inches longer than conventional units. The customer can choose either an innerspring or foam mattress, both of which are just 23/4 inches thick. Some see the thinner mattress as a disadvantage to the unit, but Len Eby, merchandise manager of Super Sagless, says the smooth sleep surface has been engineered not only for occasional overnight visitors but for those studio-apartment dwellers who sleep on the units every night.

The supporting cross bar that normally hits sleepers about midback is recessed four inches in this far less cumbersome one-piece mechanism, Mr. Eby claims. Built-in stabilizers give it strength and make it adaptable to any kind of furniture.

One of the hits of the October furniture market was the console-sleeper introduced by Pulaski Furniture Corporation, to retail around $699. It features the Super Sagless mechanism. Several manufacturers of wall systems are making them more multifunctional than ever by including in them one wall unit that contains the Super Sagless vertical couch-bed mechanism.

Hoover Universal of Lexington, Ky., brought its own trifold unit here from Europe under a licensing agreement. The company is now providing it for many furniture manufacturers, including Thayer Coggin of High Point, N.C., which has added specialty sleeper units to its sofas, love seats, chairs, coffee tables, credenzas, buffets, and ottomans. Their reception has been great, says Milo Baughman, designer for Thayer Coggin, and he plans to continue thinking of new ways to use the built-in sleeper potential.

The third manufacturer of the trifold mechanism is Leggett & Platt of Carthage, Mo. The three companies mentioned here are now supplying the furniture industry with the trifold mechanisms. Companies that have introduced new convertible sleeping pieces with the mechanisms include such leading manufacturers as Selig, Brandt, Trend Line, Futorian, and Bassett.

Jim Heune, vice-president of Trend Line, referring to his company's new sleeper-table, says, ''If a consumer has to buy a table, I think he'll want to spend another $100 and buy a sleeper, too.'' Eby, of Super Sagless, says that $ 100 is the average additional retail cost for a piece of furniture that includes a trifold sleeping unit.

One company president has reported in Retailing Home Furnishings that the trifold will not replace conventional mechanisms, but will simply provide additional flexibility in design and function. Well-known convertible sofa manufacturers, such as Simmons, plan to stick with their usual mechanisms and their thicker innerspring mattresses.