Technical Insight
Toyoda Gosei and Toshiba join forces to develop a white-light LED Untitled Document (Cover Story)
Two leading Japanese LED manufacturers, Toyoda Gosei and Toshiba, have jointly developed a white LED, which will be marketed separately by both companies under their own brand names. The white lamp combines a 380 nm InGaN-based chip, fabricated by Toyoda Gosei, with a red, green and blue phosphor in a transparent package developed and produced by Toshiba. The new device is the first example of a white LED that combines a near-UV LED with a tri-color phosphor. Other products, such as those made by Nichia, use a blue LED in combination with a phosphor that emits in the yellow region, and have poor color stability because the wavelength of the blue LED varies with temperature. In the new product, the 380 nm emission does not directly determine the color output, so the device has improved controllability and wavelength stability. The partners plan to begin shipping samples in April, with a sample price of 200300 ($1.702.60). This is roughly double the price of Nichia s white LEDs, which are more than twice as bright as the Toyoda/Toshiba product. However, Toyoda s management believes that brightness levels will match Nichia when commercial production begins in November at 500 000 units per month. The chips will be manufactured by Toyoda and packaged by Toshiba: the surface mount devices will be housed in a 3.2 2.8 mm package. Planned production will reach four million units by March 2002, by which time prices should fall to the level of Nichia s white LEDs. Target applications include the instrument panels of motor vehicles and LCD backlighting.
