Trade Resources Industry Views The First MEMS Tablets Coming by Summer 2014

The First MEMS Tablets Coming by Summer 2014

While passing by the Sharp stand at CES 2014, a super-bright 7" display caught our eyes. On closer inspection, it turned out to be a MEMS display, based on a new type of screen technology that could seriously rival LCD and OLED.

CES 2014: Sharp Shows off 7" MEMS Display, OLED Watch out!

Sharp Mems CES ecran

The First MEMS Tablets Coming By Summer 2014

Without any particular pomp or circumstance, Sharp was showing off its 7" MEMS—or Micro Electro Mechanical System—display with 1280 x 768 pixels at this year's Consumer Electronics Show. As a direct rival for OLED, MEMS could shape up to be the must-have screen technology for the tablets of the future. It may even one day find its way into TV sets, such as highly energy-efficient 8K TVs, although Sharp was quick to shrug off any such suggestions. Still, Sharp's engineers did tell us that the first tablets loaded with MEMS displays were due to land within six months' time.

CES 2014: Sharp Shows off 7" MEMS Display, OLED Watch out!_1

MEMS technology has plenty of advantages. Its backighting system, comprised of RGB diodes, is said to be much more effective than those used in other types of screen, as light emitted from the diodes doesn't have to pass through liquid crystal cells or colour filters. In fact, we've been told that display quality should be pretty much unshakable, even when viewing in difficult conditions like bright, direct sunlight, or in very high or low temperatures. Similarly, MEMS promises very low power use, as the backlighting doesn't have to work as hard as with LCD screens, whose liquid crystals and filters effectively reduce the intensity of the LED backlights.

CES 2014: Sharp Shows off 7" MEMS Display, OLED Watch out!_2

Mems outside

New Sub-Pixel Structure

But when it comes to explaining exactly how this technology works, Sharp was all for keeping things pretty vague. We do know that the backlighting system is made up of red, green and blue diodes, on top of which is a layer of MEMS micro-shutters that open and close to let through varying amounts of light. But Sharp's engineers wouldn't tell us more than that—they're probably keen on keeping their exact design under wraps. Anyway, we set about doing a little research of our own to find out more, first of all by taking a closer look at the sub-pixels hiding underneath that 7" display.

CES 2014: Sharp Shows off 7" MEMS Display, OLED Watch out!_3

MEMS display under the microscope.

And we have to admit that the photo proved pretty puzzling at first glance. Where are all the RGB sub-pixels? What on earth are those arrangement patterns? What's with that double-bar pixel structure? And can any pixel effectively take on any colour?

More on MEMS

After thinking long and hard about this new structure and doing a little digging, it seems that each of the double bars in the photo above is actually one pixel. So the MEMS system works more or less like an LCD, except that the colour filters have been removed and replaced with a set of mechanical shutters that open and close very quickly. The backlighting is made up of red, green and blue diodes arranged behind a layer of MEMS shutters. We couldn't work out whether the diodes were arranged like Edge LED displays around the sides of the screen or spread over the whole screen surface behind the MEMS shutters, like in a direct LED display with local dimming.

CES 2014: Sharp Shows off 7" MEMS Display, OLED Watch out!_4

The intensity of colour emitted is determined by the high-speed back-and-forth movement of two micro-shutters, a bit like the DLP matrix systems used in some video projectors. The speed of the shutters' oscillation and their position in turn determines the amount of light let through from the layer of red, blue and green LED backlights. The shutters stay closed to make a black pixel, and adopt various intermediary positions to determine the hue and intensity of colour required. So the part that's labelled "aperture glass" between the shutters and backlights in the diagram below should, in theory, act a bit like a lens, converging light emitted from the backlights to the shutters to channel the colours and blend them together seamlessly.

CES 2014: Sharp Shows off 7" MEMS Display, OLED Watch out!_5

Mems sharp

When we showed Sharp our sub-pixel picture and explained our theories, the engineers seemed both amused and slightly concerned, and immediately asked which publication we work for. They were also pretty amused by the level of detail captured in our sub-pixel photo. In the end, they confirmed that we were more or less on the right track, even if they couldn't answer any of our questions about the number of RGB diodes and their position in relation to the shutters. For the moment, we'll have to make do with our own theories.

First, we wondered if it's reasonable to assume that there are as many sets of red, blue and green diodes as there are pixels? Because in that case, you might as well just make an OLED display and do away with the shutters. Plus, the two engineers we spoke to were adamant that while MEMS screens will initially cost a little more than LCDs, they'll still be cheaper than OLEDs. So production costs are being saved somewhere. Maybe the answer lies with the Edge LED and Direct LED systems used in current LCD TVs. Even Direct LED displays only use 120 to 240 blocks of RGB diodes spread over the back of the screen. Edge LED models use even fewer diodes. MEMS screens could therefore work in a similar way. Considering that 280 blocks of RGB diodes give excellent results with Full HD (1920 x 1080 pixels) Direct LED LCD TVs, then 115 blocks could be enough for a MEMS display with 1280 x 768 pixels.

Within the next six months, Sharp plans to bring 7" MEMS tablet screens to market with resolution at 1280 x 768 pixels. And if you recalculate ways of chopping up the original large-sized screen panels that roll off production lines, instead of getting a whole load of small-format screens, you could instead make 22" 4K screens, 44" 8K screens and even 16K displays from 88" in size. But let's not get ahead of ourselves just yet!

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CES 2014: Sharp Shows off 7" MEMS Display, OLED Watch out!