Research Of The Key Technologies In Laser Display System

Laser display,which uses red,green and blue laser as the three primary light source,is the fourth generation display technology after digital display.It has outstanding characteristics such as large color gamut,high brightness and ultra-high definition.Due to its broad market prospects,it becomes a hot research in recent years.Based on the laser display system,this paper conducts in-depth research and innovative design on speckle suppression technology,speckle characteristics of the projection screen,and spectral width optimization of the light source.This research has important guiding significance for the design of the laser display.The research work of this article mainly includes:1.Anew speckle suppression system based on eccentric ball lens is proposed for the monolithic DLP laser projection system.By using optical design software to simulate the system,it was found that the entire speckle suppression and uniform light system has high optical efficiency and illumination uniformity.Based on the above design scheme,a laser projection prototype based on an eccentric spherical speckle suppression system was built,and the illuminance test and speckle test were performed.The test results show that by using this highly integrated speckle suppression device,it is possible to obtain a laser projection with an illuminance uniformity of 90%or more,an optical/optical efficiency of 95 lm/W,and a speckle contrast ratio of less than 3%.This indicates that the new speckle suppression system we designed has a high practical value.2.Based on the theory,the speckle characteristics of the diffuse scattering screen were analyzed and measured,and the relationship between speckle contrast and surface topography of the projection screen was studied.In the experiment,the surface height and surface topography of 17 kinds of projection screens were measured using a sophisticated probe surface profiler,and three different types of projection screens such as white-plastic screens,bead screens,and metal screens were analyzed.It is found that the standard deviation of surface undulations of the measured screens is larger than the wavelength scale of the illumination light,and the surface topography of different types of screens is highly different.Using a speckle test platform that simulates human eye vision,the speckle contrast of 17 screens was measured.It was found that speckle contrasts of 13 screens were consistent with theoretical predictions,except bead screens.Therefore,for ordinary projection screens,we can use its surface undulation height to estimate its speckle contrast.In addition,the analysis of the gain and speckle contrast parameters of the bead screen and metal screen shows that the bead screen is more suitable for laser projection display.3.Based on the princple of colorinetry and visual psychophysics,a new color threshold experiment was designed for high saturation colors,and the spectral width of the laser display light source was optimized.In the experiment,two high saturation colors were displayed and compared using a laser display system,and the color threshold was measured according to the definition method and the constant stimulus method.Further,using a laser display system,a series of light source colors having a center wavelength of 520 nm and a spectrum width of 0.1 nm to 50 nm are reproduced for the color threshold experiment.The experiment shows that,the color threshold corresponds to a spectrum width of about 10 nm when the center wavelength is 520 nm.Therefore,in the design of the laser display system,the use of a 10 nm spectral width of the 520 nm green light source can achieve both high color saturation and low speckle contrast,which makes it a more optimal choice.The main innovations of this paper include:1.This article designed a new speckle suppression system based on eccentric ball lens.Based on this system,we build a monolithic DLP laser projection display prototype,with more than 90%illumination uniformity,optical/optical efficiency of 95 lm/W,and speckle contrast less than 3%,which indicates our design has a high practical value.2.The surface topography and speckle characteristics of the laser projection display screen are studied.The quantitative relationship between the speckle contrast of the screen and the standard deviation of surface undulations is obtained through measurement and analysis.This helps to optimize the selection and design of laser projection display screen3.The color threshold experiment for high saturation color is designed,and the optimized spectrum width of the light source at a specific wavelength is obtained.This has important guiding significance for the design of laser display light source.