Mitsubishi Chemical Corporation has filed a patent-infringement lawsuit in Korea against Intematix and a distributor, over red phosphors. Intematix plans a counter-suit.

Mitsubishi Chemical Corporation (MCC), the Tokyo, Japan-based phosphor, LED and lamp manufacturer, has filed a patent-infringement lawsuit in Korea against US-based Intematix Corporation and a Korean distributor, GVP.

Filed in Seoul Central District Court, the infringement lawsuit seeks to prohibit the two companies from importing and selling certain red-emitting phosphor products in Korea.

Intematix response

Intematix quickly issued a response to Mitsubishis announcement, describing MCCs patent-infringement claims as being "entirely without merit." Intematix said that it is "confident that its red-nitride products do not infringe any valid claims under Mitsubishi’s red-phosphor Korean patent." Intematix also said it intends to vigorously defend itself against any such claims.

In addition, Intematix believes that the Mitsubishi patent is invalid and intends to commence an invalidation proceeding against Mitsubishi.

Mitsubishi complaint in detail

Mitsubishi Chemical claims that the products in question infringe a patent in Korea (no. 816693) that covers red-emitting phosphors. The patent is owned by MCC and National Institute of Material Science.

Red-emitting phosphors are commonly used in warm-white LEDs, in combination with other phosphors, to provide the desired emission spectrum.

The Korean patent no. 816693 relates to a nitride-type red phosphor commonly known as CASN and SCASN. Such phosphors have the general formula of CaAlSiN3:Eu. The patent also covers LEDs, lighting equipment, displays and other products in which such a phosphor is used.

MCC says that it owns many other patents that are also relevant to CASN and SCASN phosphors, adding: “Should a party infringe any of MCC’s patents, we will take every appropriate measure without overlooking it.”

About the Author 

Tim Whitaker is the Editor of LEDs Magazine.