Patent highlights

19 Aug 2004

The week's patent applications include a yellow-emitting phosphor which could improve the color purity of white LEDs.

•  Title: Strontium silicate-based phosphor and method thereof
Applicant: Korea Research Institute of Chemical Technology, Korea
International application number: WO 2004/067677
Scientists in Korea are trying to patent a way to fabricate a strontium silicate-based phosphor with a europium activator. The authors say that the yellow-emitting phosphor can be used in combination with a blue LED to produce white light. They add that the phosphor shows a wide emission spectrum and that the main peak can be altered by changing the concentration of europium. "When the yellow phosphor is applied in the long wavelength ultraviolet LED and an active luminous LCD, the color purity can be improved and the luminous efficiency can be enhanced," say the authors.

•  Title: Light emitting device
Applicant: Semiconductor Energy Laboratory, Japan
International application number: WO 2004/068911
Improved power efficiency and a prolonged life are two of the alleged benefits of the electroluminescent (EL) display described in patent application WO 2004/068911. In the display, one EL film is sandwiched between an anode and a cathode. A second EL film and anode are then formed up top of the cathode. "Ohmic contact of the first anode with the second anode is made to form a parallel circuit, thereby reducing the currents flowing through the electroluminescent films," say the inventors.

•  Title: Diode-pumped laser with intracavity harmonics
Applicant: Spectra-Physics, Inc, US
International application number: WO 2004/068654
Spectra-Physics, US, has applied to patent a diode end-pumped solid-state laser with intracavity frequency conversion. "The use of intracavity techniques can provide high efficiency and longer lifetime for harmonic wavelengths than comparable extra-cavity techniques," claim the authors. "[Intracavity optics] exploit the higher intensities of the fundamental beam available inside the cavity and achieve efficient harmonic conversion with lower power densities incident on the nonlinear crystals." The application also discusses setups which can produce several harmonic beams from a single laser system.

Author
Jacqueline Hewett is technology editor on Optics.org and Opto & Laser Europe magazine.