US Patent 7922355 Solid state lighting device having effective light mixing and control

A solid state lighting device includes a light mixing cavity enclosed by a diffusive output window, heat sink walls, and a light-redirection member. A plurality of circumferentially spaced apart light emitters is secured to an interior surface of the heat sink walls. The diffusive output window and light-redirection member are therefore disposed at opposite ends of the light mixing cavity. A semiconductor lighting device driver is disposed external to the light mixing cavity in electrical communication with the light emitters. Light emitted by the plurality of light emitters is reflected from the light-redirection member and from the heat sink walls prior to exiting the light mixing cavity through the diffusive output window.