KOITO and DENSO Develop World's First Mercury-Free High-Intensity Discharge Headlamp System
Provides Bright Light and Long Bulb Life Without Harmful Environmental Effects of Mercury
TOKYO, July 27 /CNW/ -- KOITO Manufacturing Co., Ltd. and DENSOCorporation have developed, along with Toyota Motor Corporation and RoyalPhilips Electronics, the world's first mercury-free high intensity discharge(HID) headlamp system. This system completely eliminates mercury fromdischarge lamps (bulbs). The HID headlamp system is installed on the ToyotaPorte, launched this month in Japan.
The HID headlamp system has a newly developed mercury-free discharge bulb,as well as a controller (ballast) that controls lighting of the dischargebulb. KOITO and Philips developed the mercury-free discharge bulb using amercury substitute. KOITO and DENSO developed the ballast for lighting themercury-free discharge bulb. Together, these developments led to the world'sfirst mercury-free HID headlamp system that provides bright lighting and longbulb life, equal to the conventional HID headlamp system.
"In 2003, about 20 percent of new vehicles had the HID discharge system inJapan," said Mikio Tsuruta, director, General Affairs Department of KOITOManufacturing Co., Ltd. "But we expect our mercury-free HID discharge systemwill expand the HID system share worldwide."
In addition to adopting the mercury substitute for the bulb, the bulb tubedesign was changed to maintain the long bulb life.
To control the lighting of the newly developed mercury-free dischargebulb, the ballast was improved to apply increased initial operating wattageand operating current to the bulb.
"Our ballast achieves an approximate 50 percent reduction in volume and 25percent weight reduction over conventional ballasts, despite its increasedinitial operating wattage and operating current," said Hiromi Tokuda, managingofficer of the Powertrain Control Systems Business Group, DENSO Corporation."We achieved these reductions by increasing the switching frequency of the DC-DC converter contained in the ballast and enhancing the heat resistance of theballast."