Research On Low-power Technology Of Medium-size LCD's Backlight Module

As the shortage of modern social energy becomes increasingly serious,energy's efficient using has become the focus of research' s emphasis.The side-in medium-size liquid crystal displays(LCDs)which use light emitting diodes(LEDs)as their backlights are the energy-hungries of the office,and the backlight module's power consumption accounts for about 60%of the whole,so the research of side-in LCD's backlight module's low-power technology is of great significance.LCD's backlight module's low-power technology exists two prominent issues,the first is that the two-stage driver circuit based on Converter of LED causes more energy's consumption;the second is that LED's light radiates then entrances the light guide plate(LGP),the radiation produces energy loss in the transmission process.Considering the two issues,this paper researches on the single-stage LED backlight driver circuit which can reduce the power's superimposing consumption of the backlight driver circuit based on the Converter,and proposes the highly efficient light guide module based on free-form which can couple light from the LED into LGP.In terms of LED driver circuit low-power technology,this paper proposes a single-stage topology's LED driver circuit,the circuit is based on the flyback topology,utilizes energy-efficient LNK6764V as the core,and uses the auxiliary winding negative feedback to achieve the control of the load in order to avoid loss caused by optocoupler feedback.Meanwhile,study the RCD clamp circuit's parameters in detail to obtain optimum design parameters,to absorb the leakage inductance energy of transformer and reduce the power loss caused by the clamp circuit.The above scheme of the single-stage topology circuit is achieved to drive the 36 LEDs connected in series 12 and 3 in parallel which theirs total power is 8.64W.To improve the utilization of LED backlight,this paper proposes an efficient light guide module based on free-form,which composed of immersion collimating lens and the off-axis freeform reflector,the light emitted from LED is collimated by the immersion collimating lens first,then converged and aggregated into the surface of the LGP by off-axis free-form surface reflector.Design the module by using differential geometry method,aplanatic principle and Snell's law,and then use MATLAB to obtain two-dimensional contour points of the module according to the above design principles,after that establish a solid model of the module by SolidWorks,finally use Tracepro to implement ray-tracing simulation of the module.Meanwhile,immersion collimating lens has been further optimized to improve the utilization of LED's light.Finally,the single-stage topology LED driver circuit is made and tested,the results show that under the same brightness of the prototype machine the average power compared to the traditional drops 1.50W about;at the same time,the simulation of light utilization of backlight module which contains efficient light guide module is tested and compared with the traditional,the results show that its light utilization increased 11.22%and improve light hotspot phenomenon.Theoretically,apply the single-stage topology LED backlight driver circuit and efficient light guide module in side-in backlight module,the power consumption of whole-machine can decrease 3.3W at the max brightness,and reduce 16.10%compare with the convention.