Interferometric Modulator

Wireless communications are an essential and continuously expanding part of modern life. Smart phones presents a number of challenging requirements on the display module, such as low power consumption, video quality speed, and viewability in a broad range of lighting conditions.

The Interferometric Modulator (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 comprise hundreds of thousands of individually addressable IMOD elements. IMOD displays represent one of the largest examples of a micro electro mechanical systems (MEMS) based device. In one state an IMOD reflects light at a specific wavelength and gives pure, bright colors while in a second state it absorbs incident light and appears black to the viewer. As clear as an image on paper, IMOD displays can be viewed in any lighting condition including direct sunlight. Two to three times as bright as other technology


The IMOD displays minimize eye strain, and their wide viewing cones are free of the inversion effects that plague polarization-based displays. Qualcomm’s new media FLO technology will enable user to watch high performance video on portable device and applications such as this need a display offering superior viewability and less power consumption. The Qualcomm’s IMOD display technology will overcome all above mentioned requirements.

COMPETATIVE TECHNOLOGY

There are four primary approaches to flat-panel displays as shown in Figure 5. Transmissive displays work by modulating a source of light, such as a backlight, using an optically active material such as a liquid-crystal mixture. Emissive displays such as OLEDs make use of organic materials to generate light when exposed to a current source. Reflective displays work by modulating ambient light entering the display and reflecting it off of a mirror-like surface. Until recently, this modulation has typically been accomplished using liquid-crystal mixtures or electrophoretic mixtures. Finally, transflective displays are a hybrid combination of a transmissive and reflective display. This technology was developed to provide sunlight viewability for transmissive displays. Being a compromise however, this type of display technology offers a compromised viewing experience. Reflective displays were invented primarily to address the shortcomings of transmissive and emissive displays, namely power consumption and poor readability in bright environments. Since transmissive LCDs require a power-hungry backlight and OLEDs require a constant power source to generate light, it makes it difficult for designers of these technologies to reach one of the ultimate goals of mobile display technology: reducing power consumption. This is especially important for battery-powered portable devices such as mobile phones, PDAs, digital music players, digital cameras, GPS units and mobile gaming devices. With efficient use of ambient light, reflective displays eliminate the backlight unit and offer both significant power savings and a thinner display module. Battery- powered devices with 10-inch or smaller diagonal displays comprise the fastest-growing segment of the $92 billion (2006) display market. According to Display Search, this segment is expected to reach $29 billion in 2009. Given that the small-display market has huge potential and even greater demands for technological refinement, it’s no surprise that it is crowded with various solutions by companies large and small. Figure 6 shows where mirasol displays reside among the many technologies that are in use or in development for the portable phone and PDA industries alone.

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  • Raj Janorkar

    Interferometric Modulator

    10 months ago