Study On Large-screen And Ultra-thin Projection Display Technology

With the rapid development of display technology, large-screen displaytechnology is becoming more maturity and perfect，LCD TV, PDP TV and projectiondisplay has become a mainstream. Among them，the projection display occupies theabsolute superiority in terms of cost and technology，it has a pivotal position in thefield of large-screen display. The requirement of projection display productstransforms to personalization, specialization and diversification due to the marketdevelopments of display technology, conventional projection display products havebeen unable to fully meet a series of requirements proposed by consumers, such asbig-screen, low-cost, portability, short-focal length, large field of view, ultra-thin,large relative aperture and high-resolution, it is very necessary to design a newlarge-screen and ultra-thin projection optical system, broaden the application marketof the projector which has been almost saturated, open a new chapter in theapplication of projection display.The specific technical difficulties of large-screen and ultra-thin projectiondisplay is: in order to achieve the size of about100inch projection screen, projectionlens of conventional display device is placed above a distance of3meters. It isdifficult to keep a large screen meanwhile to further shorten the projection distanceobjectively. In this paper, a novel catadioptric design only with a piece of asphericmirrors is proposed to solve the problem of a relatively large throw ration, breaking through the limitations of any space in use of the projector with unlimited businessopportunities and development potential.In this program, using a digital micromirror device (DMD) produced by TI Inc.as spatial light modulator, employing hybrid light with laser and LED as a highbrightness projector light, the light source is coupled and projected uniformly in thespatial light modulator through the illumination optical system, and an image isenlarged via a special imaging optical system. Based on this program, it needs tofully understand the various components of projection display system, as well asdiscussing the theoretical basis of geometrical optics on projection lens design andtechnical indicators used to evaluate the image quality of the projected image.In the design of the imaging optical system, to solve the problem of shortprojection distance to achieve a large-screen and high-brightness image, we discussthree kinds of structure respectively, such as transmissive projection lens, reflectiveoptical system and catadioptric system in the aspect of aberration correction, thedifficulty of processing and testing and application prospects. Finally, using acatadioptric imaging optical system for designing the ultra-thin structure, the systemis rotational symmetry but off-axis imaging, an aspheric mirror is employed not onlysimplifying the system configuration greatly, but also improving the performance ofimaging system. Software of Light Tools is used for tracing rays and analyzing theuniformity on the imaging plane, simulation results show that illuminationuniformity is very good on the focal plane.In order to further verify the performance of catadioptric projection lens withultra-short projection distance, the processing and alignment of projection imaginglens were completed taking into account the manufacturing costs and the test level ofaspheric surface in this paper, and a experimental prototype was set up matching theexisting DLP light source, the size of the image is65.2" on the screen at the distanceof102mm. At the same time, the main indicators such as the distortion, brightnesscontrast, illumination uniformity, etc. were tested with the test instrument, the actualmeasurements were very close to the simulation results, both meeting the design requirements, the prototype made contributions on the development of "zerodistance" and large-screen projection production on a large scale.