Apple investigating low-power LCD displays for iPhone, MacBook
This week, the U.S. Patent and Trademark Office introduced a new patent application from Apple, titled "Staggered Line Inversion and Power Reduction System and Method for LCD Panels." It describes various "inversion techniques" for an LCD display on a device like an iPhone or a MacBook, resulting in lower power consumption and longer battery life.
The application notes that with current LCD displays, the amount of light that is viewable on a particular pixel depends on the voltage applied to that pixel. Because applying a single direct current voltage could damage the pixels on an LCD, screens typically alternate, or invert, the voltage applied to the pixels between positive and negative direct current values.
But Apple said that refresh techniques used in current displays can cause artifacts or visual effects that are not easy on the eyes. In addition, the application suggests that new inversion techniques could be used to create LCD panels that consume less power.
To resolve this, Apple's invention offers a number of options, including staggered inversions with two lines, one line or any other potential number or combination.
Such a system could also include a "high impedance power reduction technique," the application states, that could be applied to "idle" lines on an LCD screen. In addition to potentially creating a display more pleasing to the eye, this could also reduce power consumption of an LCD panel.
Illustrations included with the application show the technology being applied to Apple's highly successful portable devices, including the iPhone and MacBook Pro.
The invention was first applied for on Feb. 11, 2010, and made public this year. It is credited to Yongman Lee.
Apple has shown considerable interest in improving its LCD displays on mobile devices this year. The iPad was the first portable device to employ in-plane switching technology which allows improved viewing angles and color reproductions. IPS was also introduced on the iPhone 4 this year.
In addition, both the iPhone 4 and iPod touch gained the Retina Display this year. Retina Display is Apple's branding for screens that are said to sport a pixel density so high that the human eye cannot distinguish between individual pixels.