Submitted by:
Kartik Barmera

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INTRODUCTION
WHAT IS INTERFEROMETRIC MODULAR DISPLAY TECHNOLOGY?
The Interferometric Modular (iMoD) is an electrically switched light modulator comprising a
micro-machined cavity that is switched on and off using driver ICs similar to those used to
address LCDs. An iMoD based reflective flat panel display can include hundreds of thousands of
individually addressable iMoD elements. iMoD displays represent one of the foremost examples
of a micro-electromechanical systems (MEMS) based device.
In one state an iMoD subpixel reflects light at a specific wavelength and gives a pure, bright color at one intensity while in a second state it absorbs incident light and appears black to the viewer. The wing of butterflies employs the same phenomena. When not being addressed, an iMoD display consumes very little power.
The iMoD was invented by Mark W. Miles, a MEMS researcher and founder of Etalon, Inc., and
(co-founder) of Iridgim Display Corporation. Qualcomm took over the development of this
technology after its acquisition of Iridigm in 2004, and subsequently formed Qualcomm MEMS
Technologies (QMT).[4] Qualcomm has allowed commercialization of the technology under the
trademarked name "Imod", and this energy-efficient, biomimetic technology sees application and
use in mobile phones, etc.
A major breakthrough in display technology, iMoD displays are the next generation of flat-panel
displays and promise substantial performance and power-saving benefits over current
technologies. Reflect on this: As butterfly wings and peacock feathers create color by causing
light to interfere with itself, so do the elements in a QUALCOMM display. This is why we call it
an Interferometric Modulator, or iMoD, display.
Overview of IMOD Technology
MEMS-based display technologies have been under development for over a decade, but have
only recently started to gain traction. Display systems based on arrays of movable mirrors are
now widely available in the consumer marketplace. Deformable mirrors and mechanical shutters
are also making use of MEMS-based displays. Their digital nature and fast response make them
ideal for display applications. However, their role has been limited to applications with fixedangle
light sources rather than portable direct-view displays, as they are not effective when
removed from a fixed-angle light source.
Developed to address these shortcomings, IMOD displays are based on the principle of
interference, which is used to determine the color of the reflected light. IMOD pixels are capable
of switching speeds on the order of 10 microseconds. Additionally, displays fabricated using
IMOD technology have shown reflectivities of greater than 60 percent, contrast ratios greater
than 15:1 and drive voltages of as low as 5 volts. Though simple in structure, IMOD display
elements provide the functions of modulation, color selection and memory while eliminating
active matrices, color filters and polarizers. The result is a high-performance display capable of
active-matrix type functionality at passive-matrix cost. IMOD displays are a strong contender in
the display industry, with the potential to offer many of the benefits of ink and report
Qualcomm’s Imod™ displays are a technology breakthrough that deliver substantial
performance benefits over competing display technologies. The reflective displays, based on
interferometric modulation (IMOD) technology, offer a significant reduction in power
consumption as compared to other display technologies, while extending device battery life and
enabling new features. Moreover, these displays require no backlighting and can be viewed in
bright sunlight and in a wide range of environments.
Inspired by the simplicity of natural iridescent colors, the Imod display physically manipulates
light using micron and sub-micron sized mechanical elements. These simple, elegant structures
result in a display that is:
• Highly Reflective – provides consistent viewing quality in varied environments ranging from
dim indoor lighting to the brightest outdoor sunlight
• Energy Efficient – dramatically reduces the energy consumption from the display resulting in
increased usage time across every usage models
• Inspiringly Innovative – enables increasingly diverse industrial designs and applications while
greatly enhancing the potential for carrier revenue.
This report will consider current market trends that drive the convergence of multimedia
applications onto the cellular phone and the demand this convergence places on the limited
battery budget of the typical handset.
Specifically, this discussion will center on the ever increasing gap between the energy available
and the energy demands of the handset. Similarly, this reportwill consider the convergence
driven market trend of expanding handset use in increasingly diverse viewing environments.
Finally, this report will address the solutions Imod display technology offers to these trends.
Namely, this report will illustrate the energy savings Imod displays provide, and their ability to
enable utilization of the handset throughout the entire range of illumination conditions.
Operational Principles of the Imod Display
As shown in the left-hand side of Figure 1, each pixel within a Imod display is composed of
micro-electro-mechanical-system (MEMS) elements. The display is built on a glass substrate,
and each MEMS element functions as a resonant optical cavity that strongly reflects a specific
portion of the visible spectrum. The related visual color that is created is directly proportional to
the cavity’s depth. Thin films deposited on the substrate comprise one wall of this cavity, and
the other wall is a highly reflective flexible membrane.
When electrostatic force is applied across the cavity, the membrane collapses against the
substrate films, the cavity becomes very thin, and the resonant wavelength moves into the
ultraviolet spectrum. Consequently, the viewer perceives a collapsed MEMS element as being
black or “off.” As shown in the right-hand side of Figure 1, color displays are made by
composing a single pixel from MEMS elements of different thicknesses. Varying the cavity
depth results in variations of resonant wavelengths which yield variations of color. This pixel
construction utilizes no color filters, polarizers, or organic compounds. Such simplicity leads to
high energy efficiency, brightness, and environmental stability that are the hallmarks of the Imod
design.

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