Published on November 15th, 2013 | By: Jim Destefani0
Video: Materials at heart of mobile display, battery life battlePublished on November 15th, 2013 | By: Jim Destefani
Amazon’s Kindle Fire HDX (photo above) and Apple’s iPad Air use competing next-generation LCD backplane materials to improve display resolution and battery life. Credit: Amazon.
Last week Eileen reported on the distinct possibility that Apple may be gearing up to increase its use of sapphire for iPhone touchscreens.
The company continues to make materials news, this time with regard to the display technology used in its new iPad Air tablet. As usual, Apple is not talking. But analysts say the display uses backplane electronics based on indium gallium zinc oxide, an alternative to amorphous silicon chips that offers higher resolution with significantly lower power consumption.
According to an article in MIT Technology Review, IGZO is one of two materials technologies competing to replace amorphous silicon for semiconductor applications. The problem facing designers of displays and other components for mobile devices such as tablets and smartphones is one of simple physics: new chip designs are bumping into the upper limits of amorphous silicon’s ability to transport electrons. Both IGZO and another material, low-temperature polycrystalline silicon, have much higher electron mobility than amorphous silicon, according to this article in ExtremeTech. Thus both technologies offer the promise of higher-resolution displays and reduced power consumption versus amorphous silicon.
An Apple news release says only that the iPad Air uses a new chip that allows a more compact battery design. The result is an overall volume reduction of 24% with battery life of up to 10 hr equaling that of the previous-generation device. The iPad Air’s 9.7-inch display clocks in with a resolution of 326 pixels per inch, according to the release.
Teardown experts—Apple’s refusal to divulge information about the electronics and materials technologies used in its devices has spawned an entire reverse engineering industry—say display resolution is 264 ppi. Regardless, the iPad Air display has more than adequate resolution, and efficiency is even better than Apple’s claim, according to DisplayMate Technologies Corp.’s head-to-head comparison of the latest tablets from Apple, Amazon, and Google.
“The most important under the hood display improvement is the switch from [amorphous silicon] LCDs up to a much higher performance IGZO LCD backplane,” the article states. “The switch to IGZO produces an impressive 57% improvement in display power efficiency from previous Retina display iPads—so the iPad Air doesn’t get uncomfortably warm like the earlier iPads.”
The article tests display resolution, brightness, performance under various lighting conditions, and other factors for the iPad Air; the Apple device’s main competitor, Amazon’s newly launched Kindle Fire HDX, which shipped last week; and Google’s Nexus 10. The newest Kindle uses an LTPS display backplane and is said to offer screen resolution of 339 pixels per inch—the highest of any current device. Released about a year ago, the Nexus 10 uses an amorphous silicon display backplane but still manages 300-ppi resolution. The article gives the Fire HDX display an overall grade of “A.” The iPad Air receives an overall “A-,” while the Nexus 10 rates an overall “B” grade.
Makers of mobile devices—and even of LED TVs and computer monitors—clearly will be making use of chips produced using these new backplane materials. What’s less clear is which material may eventually win out, but the bottom line, as usual, may be the bottom line: according to the MIT Technology Review article, IGZO transistor arrays are less expensive to produce than LTPS and the technology lends itself better to production of large displays. The latter material is likely to find more limited application in high-end smartphones and other smaller mobile devices, the article says.
The video in this post is produced by Sharp, one of the main suppliers of IGZO LCD backplane technology, and comes via YouTube.
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