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The Digital Micromirror Device for Projection Display
| Content Provider | Semantic Scholar |
|---|---|
| Author | Monk, David W. |
| Copyright Year | 2004 |
| Abstract | The Digital Micromirror Device is the product of a technological development program which began at Texas Instruments over 15 years ago. It is a microelectromechanical system, MEMS, device which includes an array of mirrors fabricated above CMOS static RAM memory elements. Rapid switching of the diagonally hinged mirrors allows incident light to be modulated to form the highest quality video images for projection display systems. Recent developments, discussed here, improve the optical and electronic performance as well as reduce the required number of active elements. 0-7803-2466-8195 $4.00 01995 IEEE 43 44 1995 International Conference on Wafer Scale Integration The evolution of the integrated circuit (YC) has made possible enormous progress in our ability to store and process huge quantities of data in real time environments. In the past, the end use emphasis for most of this data has been in alpha-numeric or computer graphical form. As we moved into the realm of submicron YC technologies we have managed more digital bandwidth for signal processing and the transmission of moving images. The preprocessing, transmission and post processing of these video images has now extended from standard resolution into the higher definition images and high definition video. So far, this processing progress at the silicon level has not been matched with equal advances in the display world. Certainly, we enjoy excellent performance from ever improving CRT based systems. Due to LCD technology, we can deliver slim-line, battery powered, portable computer devices, in black and white as well low bit depth color. Active matrix LCD has provided for video images of adequate quality to emerge in the portable products. The ever increasing performance quality of LCD technology in projection displays has enabled the emergence of non CRT business and professional projection displays. While LCD image quality may be short of the CRT, new display products can be enabled by trading off higher brightness against lower image quality and power efficiency. However, when it comes to the highest image quality requirements for group viewing of images, we often still tum back to the overhead or slide projectors coupled with CRT systems. What is needed is a display technology that can deliver the brightness of an overhead projector with the image quality and clarity of a CRT and be driven by a computer or video input signal. Issues of size, weight and cost of the most desired system also enter into the decison process of the display technology of need. Texas Instruments believes that, once again, I/C device technology coupled closely with the emerging video processing I/C technology, could potentially enables a solution to this requirement. Digital Light Processing solutions, DLP, a totally digital approach to projection display systems is that potential solution. Incorporating the Digital Microminor Device (DMD), TI engineers have been developing DLP solutions through engineering prototype display systems since 1992. The DLP solution leverages the ongoing advances of the DMD technology that have emerged since the DMD was invented by Dr Larry Hombeck at TI'S Central Research Labs in Dallas, Texas, more than fifteen years ago [l]. Hombeck's invention centered on the use of an integrated circuit as the foundation for a system using micro-mechanical metallic reflection. The I/C was built with amplifiers whose outputs were connected to electrodes formed at the surface of the device. This surface was covered with a metalized polymer membrane. The purpose of the metalization was to form the second 'plate' of a capacitor and also to act as a reflector of light. When the amplifier was addressed the electrodes were energised and caused an electrostatic force between them and the membrane. The individual amplifier cells were built into an x,y array so that the metalized surface could be electronically controlled. The electrostatically induced deformations of the reflecting surface were used in Schlieren optical systems to produce a display. The devices worked, and proved the concept of YC based mirror control but were not really practical for high volume manufacturing. These devices were called Deformable Membrane Displays. Session 2: Applications I1 45 Two shortcoming of this original approach were the small deformation phase differences and reproducibility of the deflection vs. voltage characteristic in large arrays. The single membrane surface was also hard to manufacture and very prone to particle contamination. The next development was to replace the single membrane surface with an individual mirror for each address point or pixel. The mirrors were fabricated using sputtered aluminium in a s imi i process to that used for conventional I/C interconnects. The mirrors were flat surfaces mounted by cantilever to a post. Each post supported 4 orthogonal mirrors via thin flexible metallic hinges. The mirrors, like the membrane, were electrostatically attracted to the address electrode. The maximum deflection angle was dependent on the perpendicular distance between the mirror and the electrode. This scheme used conventional CMOS process equipment, achieved improved deflection angles, and had better producibility since it eliminated the continuous membrane approach. The cantilevered beam deflection was an analogue of electrode voltage, so pixel to pixel consistency and linearity were more easily controlled than with the single membrane scheme. Many applications were now possible using this more practical light phase modulator and it was renamed the Defonnuble Mirror Device. The key to commercial success was seen to require a device that could operate with low voltage digital CMOS technology. As many applications were moving to the digital domain, this became even more appropriate. A new version of the DMD was thus developed as a bistable device in 1988. The DMD acronym survived the third name change and now stands for the Digital Micromirror Device the name it retains today [2,3]. A simplified diagram of the, basic digital micromirror device element is shown in Figure 1 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.computer.org/csdl/proceedings/icwsi/1995/2467/00/00515437.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Acronyms Active matrix Active-matrix liquid-crystal display Address Point Aluminum Amplifier Analog CMOS Capacitor Device Component Cathode Ray Tube Device Component Cathode Ray Tubes Clarity Measurement Diagram Digital Light Processing Digital micromirror device Display device Electrical connection Emergence Engineering Flip-flop (electronics) Graphical user interface Image quality Image resolution Inferior Wall Myocardial Infarction Instrument - device Integrated Circuit Device Component Intrauterine Devices Medication Event Monitoring System Microelectromechanical systems Modulation Modulator Device Component Movie projector Numbers Optical System Overhead (computing) Overhead projector Particle filter Performance per watt Pixel Polymer Portable computer Power (Psychology) Preprocessor Program Development Programmer Prototype Quantity Ray (optics) Recursive acronym Requirement Signal processing Silicon Slide projector Solutions Static random-access memory Tissue membrane Video processing Video projector Wafer-scale integration brightness electrode voltage |
| Content Type | Text |
| Resource Type | Article |
