With the launch of the iPhone and iPad, as well as the new Macbook, Apple has continued on its path of increasing its display resolution. Apple created the term “Retina display” not just as a marketing phrase, but to educate end users about high resolution. Apple has been leading the trend in displays with high pixels per inch (ppi, the measurement of resolution), especially with the launch of iPhone 4, the first smart phone with a resolution of more than 300 ppi, and the new iPad, the first tablet PC with over 200 ppi.
However, other smart device makers, including Samsung, HTC, Google, Amazon, Sony, Lenovo, and ASUS are closely following Apple, and in some cases have introduced products with higher resolutions, such as Google’s Nexus 10 tablet PC, with a 10.1” 2560×1600 display at 298 ppi, and coming smart phones using 5.0” 1920×1080 displays at 490 ppi.
Many speculated that Apple would introduce the Retina display concept into all of its products and keep increasing resolution, but the iPad Mini does not have a Retina display, and the iPhone 5 are not higher resolution compared to their predecessors, iPhone 4 and iPad. So will Apple continue to lead the trend of the high resolution? Or has the company decided that current resolutions are good enough, and is focusing on improvements in form factor and power consumption?
The pixel density of Apple’s iPhone 4, new iPad, new Macbook Air and new Macbook are exactly 4 times of the pixel density of their predecessors (iPhone 3, iPad 2, Macbook Air and Macbook), as shown in the figure. One possible scenario is that Apple will increase the resolution of the iPad and iPad mini display to 330 PPI, which would mean that its three main mobile devices will have Retina displays, with roughly the same resolution.
Exceeding 300 ppi in a tablet PC display may require new technologies, particularly oxide TFT (such as IGZO) because of the high electron mobility required to drive small pixels at low power consumption. Sharp was the first to mass produce oxide TFT panels, but Samsung, LG Display, AUO and Chimei are all working on oxide TFT as well, for the sake of readiness for Apple’s requirement. In addition, high pixel densities will increase backlight power consumption, and thermal dissipation of the LED is also a concern. All of these are challenges for the panel makers.
It is not yet clear whether Apple intends to upgrade the resolution of the iPad and iPad mini. However, end users are becoming used to 300 PPI and higher in smart phones, so they may be looking for the same level of the pixel density in tablet PCs.
Apple’s display resolution evolution (blue) and potential upgrades (yellow)