A chromaticity control standard “3-Step MacAdam ellipses” is implemented in mass production of white LEDs for lighting – Mass production with 1/9th of the conventional chromaticity range.

Citizen Electronics Co., Ltd (Head Office: Fujiyoshida City, Yamanashi Prefecture. President: Katsuhiko Noguchi. Paid-in capital: 1,988.55 million yen), a precision electronics manufacturer, achieves mass production of white LEDs for lighting with about one-ninth the conventional chromaticity range. Through use of "3-Step MacAdam ellipses" as a chromaticity control standard the necessary reduction in the variation in chromaticity is accomplished.

White LEDs are well-known in various fields such as for LCD TV's backlights or lighting and they require strict color control of the chromaticity range, especially in white LEDs for general lighting. Usually, the products need to be ranked and sorted according to the requirements before shipment, as the color always varies even if the products are produced in the same lot.

Since the chromaticity of a white LED is determined by a combination of many elements configuring the product such as a light-emitting device, phosphor, and encapsulation resin, a complicated process control is also needed to control those elements. Citizen Electronics Co., Ltd developed Surface Mount LED chips in 1983, and since then we have brought out a wide variety of products as a leading manufacturer of LED packages. Using basic studies and innovations of Citizen's accumulated high-precision processing technology and manufacturing technology has allowed them to finally achieve mass production with the chromaticity standard of about a ninth of the conventional chromaticity range ("3-Step MacAdam ellipses") by controlling the deviation from specific chromaticity coordinates and "elaborating" the products.

This will enable Citizen to stably produce and offer a white LED that has the least variation in chromaticity while keeping the production cost low by discontinuing the "sorting" process before shipment. It is believed that at the destination sites it will be possible to use separate LED colors with high accuracy and that will help to produce quality lighting equipment. Citizen Electronics Co., Ltd will start color control using "3-Step MacAdam ellipses" at the mass production level, taking the initiative in the lighting industry.

Marl International Limited are sole distributors of Citizen LEDs in the UK.

View the full Citizen LEDs range on our website.
Download the full press release (PDF) from the Citizen website.
Contact the Marl Optosource team for further information.