LED patent litigation remains hot, with two new lawsuits filed last month. In the first, North Carolina LED maker Cree sued SemiLEDs Optoelectronics (SemiLEDs), alleging that SemiLEDs’ MvpLED product line infringes six patents.
The complaint (Cree-Semileds-Complaint), filed in U.S. District Court for the Middle District of North Carolina, asserts U.S. Patent Nos. 7,737,459 (‘459 Patent), 7,211,833 (‘833 Patent), 7,611,915 (‘915 Patent), 6,657,236 (‘236 Patent), 7,795,623 (‘623 Patent), and 7,557,380 (‘380 Patent).
The ‘833 and ‘915 Patents are part of a family that relates to gallium nitride LEDs having a silicon carbide (SiC) substrate in a “flip-chip” mounted configuration, i.e., the LED is mounted so the substrate side faces upwards away from the LED package, or submount.
An LED (100) includes a substrate (20) and an epitaxial region (30) on the substrate. There is a multilayer conductive stack (35) and an ohmic layer (32) on the epitaxial region (30) opposite the substrate (20).
A reflector layer (34) is on the ohmic layer (32) opposite the epitaxial region, and a barrier layer (36) is opposite the reflector layer (34).
According to the ‘833 and ‘915 Patents, this configuration has several advantages over existing SiC-based LEDs, including increased resistance to high temperatures, higher shear strength of bonds between the LED and the submount, and improved conductivity.
The ‘236 Patent is directed to LEDs having light extraction structures, which boost efficiency by reflecting, refracting or scattering light so that more light escapes the LED.
The ‘380 and ‘623 Patents relate to LEDs having a reduced conductivity region aligned with a non-transparent feature such as a wire bond pad, and the ‘459 Patent is directed to an LED having particular output characteristics (radiant flux at 20 milliamps current of at least 29 milliwatts at its dominant wavelength).
In the second case, a Japanese company called Takion sued a host of LED manufacturers including GE, LEDtronics, Sharp, Philips, and Toshiba for infringement of U.S. Patent No. 6,577,072 (‘072 Patent).
According to the complaint (Takion-GE_Complaint), filed in federal court in Seattle, various LED lamp devices produced by the defendants infringe the ‘072 Patent, including GE’s LED7PAR20/NFL, LEDtronic’s ATS-200R-5 LED traffic light replacement lamp, and Philips’ 5E-26A60 product.
The ‘072 Patent is directed to an LED lamp and power supply unit that can be directly connected to an AC power supply. The power supply unit includes a wave rectifier and an electric power output.
The unit is configured so the output admits electric power only when the voltage of the rectified wave corresponding to each half period of the wave of the AC power supply voltage is equal to or heigher than a predetermined value.
According to the ‘072 Patent, the invention allows direct connection of the LED lamp to an AC power supply without unduly comprising efficiency or losing too much power by heat dissipation.