Preparation Of Uniform Side-Glowing Polymer Optical Fiber And Its Application To The Directional Backlight

Compared with the slit grating type,the cylindrical lens autostereoscopic display technology has the advantages of high display brightness,more comfortable viewing,but also has the disadvantages of high cross-talk,loss of resolution and the balance of scale,high requirement of post lens and pixel bonding,complex structure,moire fringe,and the like.Thus,the directional backlight display technology becomes the ideal autostereoscopic display technology.Through the analysis of theautostereoscopic display technology of the existing directional backlight,an autostereoscopic display solution for directional backlight of an optical fiber backlight source is proposed,a uniform side-glowing polymer optical fiber is prepared by laser marking technology and used as a novel backlight source,so that the structure of the existing autostereoscopic display can be simplified,the technical requirement can be reduced,and the advantages of no resolution loss of the traditional directional backlight display technology can be retained.The uniform side-glowing polymer optical fiber is used to replace the light guide plate and the LCD switch in the prior directional backlight technology,a line light source array is used for replacing the surface light source,so that the image crosstalk and the structural complexity of the backlight source can be reduced.First,the principle of directional backlight display technology is introduced.In the traditional technology,the LCD switch panel is placed in front of the backlight.By adjusting the on and off of each row of pixels on the LCD switch panel,the backlight is projected directionally and refracted through the cylindrical lens,and it is emitted along the specific propagation direction of each other.The problems of crosstalk in traditional technology is solved.The problem of high crosstalk in traditional technology is solved.In this paper,the problems of complex structure,excessive brightness loss and uneven distribution in the existing directional backlight display technology are analyzed,and a solution of uniform side-glowing polymer fiber as directional backlight source is proposed and designed.A method for preparing a uniform side-glowing polymer optical fiber(POF)is introduced.Varied-line-space(VLS)gratings were fabricated on the side of the POF by laser-marking technology.The model of scattering points of VLS gratings fabricated by laser was established.The model was composed of shallow surface pits and the scattering area in the core,in which scattering particles were distributed.The relative scattering power of scattering points and the calculating formula of VLS were derived theoretically.The rule of the scattering light power varied with the depth of the pits and the density of scattering particles at the scattering points was analyzed.The distribution rule of VLS grating pitch under different pits depth of scattering points and different relative emissivity of the side-glowing POF was also discussed.The results showed that the small variation(micron dimension)of the pits' depth in scattering points had great influence on the scattering light power and the VLS grating pitch.When the density of scattering particles was,the power of scattering light power didn't vary with the density of scattering points.And if the density of scattering particles was,the scattering power varied obviously with the density of scattering particles.The distribution curves of the VLS grating pitch with different pits' depth and different relative emissivity were calculated theoretically.And the validity of the theoretical results was verified by experiments.By adjusting the proper laser marking power,the side-glowing POF with brightness uniformity of more than 90% were obtained.Finally,the model of uniform side-glowing polymer optical fiber is applied to the backlight module of autostereoscopic display by software simulation.The 18 lines / inch cylindrical lens grating plate is used,and the POF diameter is 0.25 mm to build the model through Solidworks.Ten positions are selected in the square focal plane of the cylindrical lens in the model,and the light emitting surface of the uniform side –glowing polymer optical fiber is placed at the selected 10 positions in turn.Through Tracepro simulation,the irradiance distribution map corresponding to each position is obtained on the receiving screen.The relationship between the irradiance distribution and the position of the fiber is observed,and it is verified that the uniform side-glowing polymer optical fiber can be used in the directional backlight source.