LED backlighting system with closed loop control

摘要

A light emitting diode (LED) based illumination system with particular application to large scale side lighted liquid crystal displays (LCD). The invention uses on board closed loop intensity control in conjunction with red, green and blue (R,G,B) LED die and a hybrid non-imaging optical system to overcome substantial temperature dependence, loss in intensity with time, increased system cost and complexity, and decreased dynamic range. The invention obtains a large color gamut in excess of 110% of the NTSC (National Television System Committee) recommendation. A high performance thermal management design, the use of “chip on board” technology, compact and efficient collection optics, and on board closed loop intensity control increase and maintain luminous performance and decrease cost relative to less efficient RGB LED approaches. One or more line sources can be generated for applications other than in lighting LCD displays.

主权项

1. Illumination apparatus for producing high intensity line sources of uniform intensity and spectral content, said illumination apparatus having an optical axis and comprising:
an elongated support member having formed thereon a linear array of regularly spaced apart individual LED modules each of which comprises one or more LED emitting areas having a predetermined spectral output that is emitted directly over a predetermined solid angle; an elongated collection optic having an array of individual regularly spaced apart non-imaging concentrators the individual non-imaging concentrators of which are directly optically coupled in one-to-one correspondence with said regularly spaced individual LED modules, each non-imaging concentrator in said array of non-imaging concentrators having an entrance aperture, and exit aperture, and a cross-sectional rectangular shape that continuously curves and enlarges from said entrance aperture to said exit aperture, each of said LED emitting areas being positioned in a corresponding one of each of said entrance apertures of each non-imaging concentrator so that each non-imaging concentrator operates directly to collect substantially all of the radiation emitted by each of said LED emitting areas and to re-emit substantially all of said collected radiation as a diverging beam having a solid angle smaller than said predetermined solid angle over which radiation is emitted by each of said LED emitting areas where said diverging beam is spatially and spectrally uniform in the near field of said exit aperture and propagates in a direction along an optical axis of said apparatus, and wherein each of said non-imaging concentrators having pairs of spaced apart opposed surfaces that operate to control the divergence of said diverging beam in vertical and horizontal planes mutually perpendicular to said optical axis; and an elongated cylindrical optical lens positioned to receive said diverging beam and converge it in a vertical plane to form a line source of predetermined dimensions.