Timothy J. Hogan

Burn-in test reduction for the digital micromirror device (DMD)

Burn-in test has long been used in the semiconductor industry to screen out manufacturing defects. MEMS technologies, such as the DMD, can also use burn-in test to eliminate infant mortality failures. Burn-in test and test systems are among the most costly however, and it is always under review to shorten time or increase efficiency without reducing effectiveness. Detailed failure mode analysis from many thousands of device test logs resulted in the development of a novel application of an observed stress factor. Burn-in test time was reduced 55% on high volume DMD products with increased test efficiency and effectiveness.

CMOS Compatible Fabrication Processes for the Digital Micromirror Device

DLP® technology has been widely used in the display products since it was first introduced to the world in 1996 by Texas Instruments. Projectors powered by DLP® technology range from cinema projectors that light up large movie theater screens to palm-sized “Pico” projectors. The heart of the technology is the digital micromirror device (DMD) that features an addressable array of up to 8 million microscopic mirrors. DMDs are fabricated using standard semiconductor processing equipment. However due to the unique nature of MOEMS application and digital operation of the DMDs, special CMOS-compatible fabrication processes have been developed to produce highly reflective digital micromirrors with robust operation margin and long term reliability. This paper will present an overview of the fabrication processes of the DMDs.

Microdisplay modules for enhanced system integration

Kopin’s recently introduced low-power “Jewel Module” family of plug-and-play integrated AMLCD microdisplay modules are fully-tested, off-the-shelf assemblies that can be easily integrated into customer products without the need for an expensive application-specific development. The “Jewel Module” is the culmination of many years of technology advancement that has reduced the size and power for all of the elements of the display system: microdisplay, LED backlight, display driver ASIC, video FPGA, heater and display controller. This paper presents the performance characteristics of both current and planned modules with display resolutions from 640x480 to 1280x1024 as well as development roadmap. Applications of the “Ruby Module” with SVGA microdisplay are described with examples of its integration into display system products.

Microdisplay contributions to system level performance

Todays modeling software for infrared and fused systems ignores display performance characteristics and their impact on overall system performance. Although the implications of sensor performance and image processing with respect to system performance are well understood, the impacts of display image quality and their effects on man portable system performance are neglected in system level analysis software such as NVTherm. In addition, production test methodologies for fielded thermal systems often utilize a composite video output signal to characterize thermal camera performance but fail to characterize the impacts of display performance at room temperature and over the complete operating temperature range. This paper characterizes several key display parameters of active matrix liquid crystal displays (AMLCD) and organic light emitting diode (OLED) microdisplays that are in volume production for night vision application, and examine their effects on the performance of infrared and fused imaging systems. We present test data of contrast, gray scale rendition and fixed-pattern noise of these displays over ranges of luminance and temperature, evaluating the impacts on system level Minimum Resolvable Temperature (MRT). We conclude that the performance of thermal and fused systems can be significantly degraded based upon the display technology implemented and the system impacts of display performance can no longer be ignored by the community at large. The data indicates that modeling software such as NVTherm should be upgraded to include display performance parameters and their impacts on overall system level performance.