Idemitsu Kosan, a Japanese oil company, announced on October 17 that it has improved the service life of light-emitting materials for OLED displays. Materials for blue light have seen their lifespan increased to 23,000 hours and those for green light to 100,000 hours. Until now Idemitsu Kosan's blue light lasted only 10,000 hours, which is about the minimum to use OLED displays for the main screens of mobile phones, whereas with the upgrade OLED displays can definitely be used for this purpose. The company plans to start selling the materials to OLED display producers on a trial basis in April 2006, aiming for use in mobile phones, car navigation systems, and portable music players.