Posts Tagged ‘ Mirasol ’

Qualcomm’s Mirasol display stays small, for now

Qualcomm’s Mirasol display stays small, for now.

Peter Clarke

9/17/2010 5:42 AM EDT

LONDON – Qualcomm is focused on 5.7-inch diagonal and smaller applications for its Mirasol display right now, even though there is no technical reason why the technology could not address larger applications, according to Cheryl Goodman, director of marketing for Qualcomm MEMS Technologies.

On key stopping off point in display scaling has become the 9.7-inch size popularized by Apple with its iPad tablet computer, Goodman acknowledged.

“Qualcomm is super-connected to what’s happening in the mobile device where Mirasol can offset the problem of power consumption,” said Goodman. “First out will be a 5.7-inch e-reader.” Goodman said that rather than scaling to a larger sized display Qualcomm was likely to add smaller sizes tuned to the needs of the smartphone. The 5.7-inch display has a resolution of 1,024 by 768 pixels at 220 pixels per inch.

The Mirasol technology, which Qualcomm (San Diego, Calif.) acquired in 2004, can save power as it is non-volatile, does not require a back-light and is reflective, making use of ambient light. However, by the same token the display could be seen as less intense and visually appealing than a saturated emmissive display, such as OLED (see Comment: Qualcomm’s MEMS display is smart but is it bright enough?)

Mirasol is based on a MEMS structure combined with thin film optics to create interferometric modulation. The color display is thin and bi-stable so that power is only consumed when changing the status of display. This has the disadvantage that grey-scale requires the application of spatial and temporal dithering. Nonetheless the display is capable of running video at 30-frame per second.

“It is difficult, challenging stuff,” said Goodman, adding “There’s no fundamental reason why the technology could not go larger [than 5.7-inch diagonal].”

Goodman acknowledged that Apple’s launch of the iPad had created a consumer appetite and expectation around the 9.7-inch display size. “We would be remiss if we didn’t investigate that.”

Qualcomm has a dedicated Mirasol 4.5-generation display fab in Taiwan set to deliver in volume in 4Q10 so Mirasol displays are expected to turn up in products in 1H11. A year previously the e-reader design win was expected to deploy in fall 2010.

Goodman declined to comment on reports that Qualcomm is looking to spend as much as $2-billion to build a follow-on display fab.


Comment: Qualcomms MEMS display is smart but is it bright enough?

Comment: Qualcomms MEMS display is smart but is it bright enough?.

Peter Clarke

11/24/2009 11:32 AM EST

LONDON — Last week I was able to look at examples of the Qualcomm MEMS display, known as Mirasol.

I saw small monochrome displays in cell phones and a 5.3-inch full-color unit, posing as an e-reader display. It is a nice looking and technically elegant piece of work. It is a thin, bi-stable, reflective display that therefore theoretically only needs power for changing the image. And it is available in full color with spatial dithering of sub-pixels to provide grey-scale.

A 5.3-inch diagonal full-color Mirasol display

It uses ambient light rather than a backlight, which is its main source of its power saving. Liquid crystal displays after all use a powerful backlight and electro-optic shutters to prevent more or less of the light getting through the panel. The use of ambient light is good outdoors, where LCDs perform badly, but does mean that in low-light conditions the display is hard to read, just like it is hard to read from paper when the lights are out. Qualcomm’s solution is an occasional-use front light.

So what is not to like about this “green” full-color display?

Such a display obviously has great potential in mobile applications where power consumption and battery life are key issues. Depending on the application, a bi-stable non-volatile display can more than halve power consumption in applications such as a smart phone or an e-reader.

However, Qualcomm documentation illustrates a Mirasol scheme that uses spatial dithering to achieve only 3-bits of grey scale or 512 colors. It discusses the addition of temporal dithering to extend the grey-scale to 6-bits per primary color pixel. This gives 64 levels for each of the red, green and blue sub-pixels or a total of 256-k colors. But such a scheme would require the pixels to be continually moving and therefore consuming power.

Qualcomm MEMS Technologies Inc. commissioned a report by Pike Research LLC (Boulder, Colo.) which found that a mobile device using an IMOD (interferometric modulator display), such as Mirasol, would consume 33.7 percent less energy compared with a similar mobile device that uses a conventional LCD display. However, this was based on a 2.4-inch to 2.8-inch diagonal display and it is not clear whether it took into account any temporal dithering of the display. The report goes on to give extensive “green” and sustainable characteristics to the IMOD display.
Sticking point
But for me there is one sticking point that could inhibit take up of the Mirasol display. It is more to do with human behavior and preferences than technology, and the Pike Research report does touch upon it.

“Pike Research estimates that reflective display technology could capture greater than 20 percent market share in mini-display sizes between 2.5 and 10 inches over the next five years with an increasing percentage over time if the operational characteristics of the displays are perceived, first by OEMs and then by potential customers, as equivalent to an LCD,” the report states — but the italics are mine.

My experience is that the Mirasol display is nice to look at but nowhere near as impactful as a backlit liquid crystal display. Qualcomm claims Mirasol displays offer reflectivity on the order of 50 percent and contrast ratios greater than 8:1. It, of course, consumes far less power than a backlit LCD, but the eye does not see that.

So a big challenge for Qualcomm is that many consumer buying decisions are made not in the head as the result of trading off power consumption versus readability metrics but in the heart after seeing a glossy presentation slide across a display. Except for the most ardent of eco-warriors, most consumers expect the battery life of their toys and gadgets to be significantly improved WITHOUT reducing the brightness and attractiveness of the display. And liquid crystal displays have set the bar high.

And the designers and creators of mobile phone and netbook computer specifications know this and, on many occasions, will select the display technology that gives them the best chance of making that heart-led sale. On the other hand, if you are an eco-warrior your heart will seek out the low-power solution.

Qualcomm’s approach to displays – Small Times

Qualcomm’s approach to displays – Small Times.

by Neha K. Choksi

March 31, 2010 – Displays are a hot topic, especially in the mobile consumer electronics industry. LCD displays are prevalent in today’s handheld devices, but their poor power efficiency and readability in bright light give incentive to uncover alternative approaches. Qualcomm senior engineer Rashmi Rao shared the company’s MEMS-based approach to displays at the IEEE Bay Area Nanotechnology Council meeting on March 16, 2010.

Handheld devices are being used more and more during each day, which has large implications on the battery life of a device. Pike Research predicts that by 2014, 54% of cell phone battery life will be used toward displays. The current trend to address the issue has been to use heavier, thicker batteries, but Rao questions whether this is the true solution. Qualcomm’s mirasol display approaches the issue by trying to reduce the power consumption rather than increase battery size — an approach inspired by nature. Butterfly wings are made of millions of nanostructured etalons (two parallel reflecting surfaces). When light passes through the wing’s multilayered surface, it reflects multiple times, which leads to the intense, iridescent color for which butterfly wings are known.

Mimicking the butterfly, the company approaches a low-power display solution by creating a MEMS etalon device (see figure below). The top layer of this two-layer device is a partial reflector; the bottom layer is a total reflector. By defining the gap size between the two layers, the resulting reflected color can be specified. The bottom layer of the MEMS etalon is a moving membrane; thus the gap between layers can be modulated. The device operates as a bistable capacitive/electrostatic switch. The bright, open state is achieved by a low constant bias. By superimposing a short positive pulse, the movable bottom layer collapses for the “closed” state. The collapsed membrane results in an interference pattern of light that is not visible or “dark” to the viewer. This closed state is maintained until another pulse “un-writes” the device and the lower membrane moves back to its initial open state.

Because the device maintains its state unless pulsed, it is able to achieve lower power consumption than LCD and OLED display technologies that dominate the market today. Furthermore, Rao explains, the display is able to achieve a faster refresh rate and is also lighter than current displays. The device’s response time, on the order of microseconds, indicates that it is well suited for video applications. Also, color filters that reduce brightness in LCD technology are unnecessary for the MEMS-based display.

Brightness is a key differentiator for this display in yet another way. Because the intensity of current display technology is limited by the illumination source, which cannot compete with the intensity of sunlight, LCD and backlight OLED displays are difficult to read in bright sunlight. But since the mirasol MEMS display depends on ambient light for its light source, it has an inherent mechanism for adjusting its brightness to its surrounding light intensity, lending itself to bright light conditions. In fact, the company claims excellent contrast: 90% reflected light in the open state vs. 1% in the dark state. Plus, by utilizing ambient light, the new product eliminates the need for backlight illumination and further reduces power consumption.

On the other hand, in darkened rooms or at night, the ambient light may be insufficient for these MEMS-based displays to reflect. Hence, is Qualcomm exploring the option of frontside illumination for low ambient light conditions. It is unclear what impact the frontside illumination will have on battery life, but the aim is to keep power usage well below current LCD and OLED technology.

When asked about reliability, Rao explains that a universal usage model is still < in the industry, thus complicating a metric for comparison to other devices. The company has conducted initial accelerated lifetime tests on the device in the operational temperature range, with and without humidity, but additional investigations are underway.

Despite work to be done, the new device has received significant attention — the display technology is targeted for the e-book market. Just as cell phones are demonstrating the intersection of technology with the Internet, cameras, gaming, TV/video, contacts, music, calendar, email, and more, Qualcomm’s MEMS displays have opportunities that can reach far beyond its initial entry point. But MEMS are just one of many approaches to next-generation mobile displays, and the company is not alone in pursuing a MEMS-based approach. As Rao states, “convergence is inevitable,” and the company hopes to be on the front line as the push for energy efficiency continues.