Toshiba Corp., the first maker of 3-D televisions that don't require the use of special glasses, sold fewer than half the sets it targeted in the initial month of sales.

Toshiba, which began offering the TVs in late December, sold 500 of the 20-inch model at about ¥240,000 each, and even fewer of the cheaper 12-inch set, Masaaki Osumi, president of Toshiba's Visual Products Company, said in a recent interview. The Tokyo-based company, which ranks second in Japan in TV sales, had planned to sell 1,000 units of each model a month.

The slower-than-anticipated debut indicates the company needs to offer larger sets to appeal to consumers, Osumi said. Toshiba joins Samsung Electronics Co. and Sony Corp., which began selling their own 3-D models last year, in saying demand has lagged expectations, damping optimism consumers will embrace the technology and help TV makers revive profits.