Toyoda Gosei Develops White Light LED Jointly with Toshiba Corporation
-- The new gallium-nitride (GaN) LED with a short peak wavelength of 380 nanometers will be combined with a phosphor-mixed package --
Aichi (Japan), February 9, 2001—Toyoda Gosei today announced the introduction of a new white light emitting diode (LED) that it has developed jointly with Toshiba Corporation. Integrating Toyoda Gosei's GaN-based LEDs and Toshiba's phosphors, the white LED will be marketed and sold by the two companies under their own brand names. Toyoda Gosei will start shipping samples of the product, named TG White, in April 2001 and begin full-scale production in November 2001. The sample price for the TG White will be set at between 200 and 300 yen.
The new white LED boasts excellent stability and brightness, with a short peak wavelength of approximately 380 nanometers (nm). Its development capitalizes on Toyoda Gosei's expertise in GaN-based LED devices, an area the company has promoted since 1995 with technology for the mass production of blue and green GaN-based LEDs. The diode for the TG White will be manufactured by Toyoda Gosei and combined with a phosphor-mixed transparent resin package developed and produced by Toshiba.
The new LED product adopts a different technological approach from the one used in conventional LEDs. Instead of relying on changes in temperature to achieve changes in color output, the TG White deploys phosphors to control light emission in the visible wavelength band. Because the emission does not directly determine the color output, the new LED product can guarantee overall control and stability of wavelength. Consequently, when the new LED is incorporated in liquid crystal displays (LCDs), it achieves improved tonic reproduction and enhanced color durability during changes in temperature.
The new white LED holds out great promise as a high-luminosity, low power-consumption light source that could replace the use of incandescent lamps in the future. Current applications of white LEDs include the gauge and meter displays on automobile instrument panels and LCD backlighting.
The joint development and commercialization of the new white LED by Toyoda Gosei and Toshiba represents a new alliance to spearhead innovation in LED lamps. Toshiba, a leader in indium gallium aluminum phosphide (InGaAIP) LED since 1991, offers a variety of LED products for automobile applications, such as high-mounted stop lamps and gauge and meter displays on instrument panels, while Toyoda Gosei has pioneered the development of GaN-based LED devices. Both companies will continue to build on their current technologies to jointly develop LED products with brighter colors.
Major Characteristics of White LED
The new GaN LED emits a short wavelength light source by reducing the volume of indium inside an indium-doped GaN emission layer. The short wavelength light excites red, green and blue phosphors in the transparent resin of the device package to output white light. The emission light from the LED itself does not directly contribute to the white color.
the color output, and different colored outputs can be achieved by adjusting the phosphor output balance. The phosphors used in the new LED offer excellent color yield and performance in terms of the operating temperature range.
- Main Specifications of New LED
Package 3.2 x 2.8 millimeter, Surface Mount Device (SMD) Luminosity Typ. 100 millicandela (mcd) at 20mA Luminous flux / Electrical watt Typ. 4.5 — 5.0 lumen per watt at 20mA Correlated color temperature 6,500 — 9,000K Operating temperature -40 — 100 centigrade Storage temperature -40 — 100 centigrade