In 2004, Lora and Richard Rosene had an idea: Create a way to heat swimming pools by using an inflatable device that would act like a magnifying glass, intensifying the sun’s rays. The result was Solar Sun Rings, and the manufacturer grew at a rate of 230 percent annually, offering its product in five continents, according to the Rosenes.

But trouble began in 2009, when Wal-Mart officials asked the Rosenes to provide their product to the discount chain. The couple declined, not wanting to destroy the relationships they had built with the 600-odd small businesses selling Solar Sun Rings, said Lora Rosene.

Then in 2010 a product similar to Solar Sun Rings, called the “Solar Pad,” began to appear in Wal-Mart stores. When the Rosenes objected, Wal-Mart’s supplier made an offer to license the Solar Sun Rings technology but, according to Lora Rosene, they again declined. Meanwhile, sales of Solar Sun Rings dropped as the Solar Pad has worked its way into more Wal-Mart outlets.

“We’ve lost $3 million in sales so far,” Lora Rosene said

Now the Rosenes, who employ 10 people in their Temecula, Calif. operation, have sued Wal-Mart, the world’s largest retailer, for patent infringement.

“We spent all this money on patents and somebody comes in and steals everything,” Lora Rosene said.

Wal-Mart, however, sees it differently. “Wal-Mart respects the intellectual property rights of others,” stated Randy Hargrove, a company spokesman. “Four of the five patents at issue in the case have already been dismissed. Wal-Mart has investigated the claims regarding the remaining patent and we are confident in our position that the patent has not been infringed.”

Yet the court may not agree. On Oct. 31, a federal district judge rejected a motion by Wal-Mart attorneys for summary judgment, stating that retail giant had not proven it impossible for a purchaser to confuse the Solar Pad for the Solar Sun Rings. Another motion for summary judgment, claiming invalidity of the Solar Sun Rings patent, also was denied.

On Dec. 5, the Rosenes and Wal-Mart are scheduled to meet in a Los Angeles court. At issue is whether the Solar Sun Rings qualify for a patent, and whether Wal-Mart is violating the patent by selling the Solar Pad.

Solar Sun Rings are made from two sheets of heavyweight vinyl; a transparent top layer and a dark blue bottom layer, with air trapped between. The blue layer absorbs about 50 percent of the sun’s rays, converting that e nergy to heat. The remaining rays get through to the pool below to provide deep-water heating. Normally, enough Solar Sun Rings are placed on the pool to cover about 70 percent of the water’s surface. They’re held together by magnets on the edge of the rings.