By a News Reporter-Staff News Editor at Journal of Engineering -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Kurtz, Andrew F. (Macedon, NY); Nothhard, Gary E. (Hilton, NY), filed on March 15, 2013, was published online on March 13, 2018.
The patent's assignee for patent number 9915820 is IMAX Theatres International Limited (Dublin, IE).
News editors obtained the following quote from the background information supplied by the inventors: "The motion picture industry is presently transitioning from traditional film-based projectors to digital or electronic cinema. This trend is accelerating due to the popularity of three-dimensional (3-D) movies. Even as digital cinema projection has matured and succeeded, largely based on the use of Digital Light Projection (DLP) technology, both the light sources and the DMD modulators have been evolving. In the case of lasers, high power compact visible lasers are becoming increasingly mature and cost competitive, enabling the development of laser digital cinema projectors. One such system is described in the paper 'A Laser-Based Digital Cinema Projector', by B. Silverstein et al. (SID Symposium Digest, Vol. 42, pp. 326-329, 2011).
"At the core of the DLP technology, which was developed by Texas Instruments, is the digital micro-mirror device (DMD), which is a spatial light modulator that includes an array of micro-mirrors. DMD spatial light modulators have been successfully employed in digital projection systems, including digital cinema devices that meet the DC2K digital cinema resolution standard. Efficiency measurements have been performed on such systems that use the DC2K chip and have found the efficiency optimizing principles to be valid; however, for systems utilizing the new DC4K chip the principle was not found to work as well.
"Early in the development of the DMD device technology, the individual micro-mirrors 55 or pixels were relatively large, at .about.30 .mu.m square. Subsequently, device resolution has improved, with progressively smaller pixels, evolving from .about.17 .mu.m square in the late 1990's, to 13.8.times.13.8 .mu.m for the 2K digital cinema projectors (2005), and more recently, reaching 7.5 .mu.m.times.7.5 .mu.m pixels with the DC4K devices (2011). The projector described by Silverstein et al used 2K resolution DMD devices for image light modulation, and various aspects of DMD device behavior were taken into account. As another example, in the paper 'Laser Digital Cinema Projector,' by G. Zheng et al., published in the Journal of Display Technology, Vol. 4 (2008), a laser projector is described that also uses the DC2K versions of the DMD devices, but with conventional DLP projection optics, including the TIR and Philips prism assembly. Notably, both Silverstein et al and Zheng et al describe projectors using the DC2K versions of the DMD devices, meaning that they were compliant with the DC1 digital cinema projection specification and provided '2K' horizontal resolution.
"However, as noted above, the recently released DC4K devices have much smaller pixels to support the higher horizontal resolution standard. As the size of the micro-mirrors decreases, diffraction effects become increasingly important, and the micro-mirror array can be thought of as a programmable blazed grating. Diffraction becomes an even larger concern when laser light interacts with these small pixel and sub-pixel features. Essentially, diffraction effects cause an efficiency loss versus a plane mirrored surface as some light is directed into other diffracted orders, which the blaze then partially restores.
"Some aspects of the diffractive behavior of the DMD devices have been considered in the literature. In particular, Texas Instruments provided some guidance concerning the interaction of laser light, in their publication 'Using Lasers with DLP.RTM. DMD technology', TI Tech Note TI DN 2509927, September 2008. However, additional practical guidance on the diffraction behavior that aids projector design is needed. A subsequent paper 'DMD diffraction measurements to support design of projectors for test and evaluation of multispectral and hyperspectral imaging sensors', by J. P. Rice et al., published in the SPIE Proc., Vol. 7210 (2009) provides infrared (IR) light diffraction efficiency measurements for IR optimized 2K resolution DMD devices. However, this paper does not discuss the optical propagation behavior of the diffracted light, and how that might affect projector design, whether in the IR or other spectral ranges.
"In summary, as micro-mirror array spatial modulators such as the DMD devices have migrated to yet smaller pixel dimensions, and laser projection systems have become increasingly feasible, the specifics of the interaction of the laser light with the micro-mirrors, which are dynamic diffractive structures, becomes more important. Therefore, opportunity exists to better understand the subtleties of micro-mirror array diffraction behavior and optimize projector design accordingly."
As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "In some aspects, an optical system can provide modulation of an incident light beam. The optical system includes an illumination source, a micro-mirror array optical modulator, and an optical element. The illumination source can provide the incident light beam that has a defined narrow spectral bandwidth. The micro-mirror array optical modulator can selectively modulate the incident light beam to encode data thereon based on commands to an ON-state or an OFF-state of one or more micro-mirrors. The micro-mirror array optical modulator can redirect light by both diffraction and reflection to provide an output modulated light beam that exhibits a diffraction handedness dependent described by an arrangement of diffraction orders that depend in part on the narrow spectral bandwidth of light incident thereupon. The optical element has an optimized limiting aperture for defining portions of a modulated light beam that are blocked and remaining portions that are transmitted. An ON-state efficiency and an OFF-state contrast of an optically transmitted modulated light beam acquired by the optical element can depend on the diffraction handedness of the output modulated light beam relative to a size and a shape of the optimized limiting aperture.
"These illustrative aspects are mentioned not to limit or define the disclosure, but to provide examples to aid understanding thereof. Additional aspects and features are discussed in the Detailed Description, and further description is provided. Advantages offered by one or more of the various aspects and features may be further understood by examining this specification or by practicing one or more aspects and features presented."
For additional information on this patent, see: Kurtz, Andrew F.; Nothhard, Gary E.. Projector Optimized for Modulator Diffraction Effects. U.S. Patent Number 9915820, filed March 15, 2013, and published online on March 13, 2018. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=9915820.PN.&OS=PN/9915820RS=PN/9915820
Keywords for this news article include: Europe, Ireland, Business, Technology, IMAX Theatres International Limited.
Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2018, NewsRx LLC