Apple will this year launch its iPhone 13 (unconfirmed) series this year. While the iPhone 13 will be an upgrade over the iPhone 12 series in almost all aspects, however, it will bring a much-awaited feature to the upcoming iPhone models - a high refresh rate display. Most recently, known display analyst Ross Young has suggested that the upcoming iPhone “Pro" models will be equipped with an LTPO display that will enable the 120Hz refresh rate. Young refuted rumours of only one iPhone 13 model featuring an LTPO display. Now, an LTPO display is something we have heard about a lot in the past - from the Samsung Galaxy S21 series, to the OnePlus 9 series, and now there are rumours of Apple using an LTPO backplane on the iPhone 13 display. So what is an LTPO? And how does it help in making a smartphone’s display better? We’ll tell you.
So LTPO stands for Low-Temperature Polycrystalline Oxide. It is essentially a piece of hardware that enables variable high refresh rate on a smartphone based on the content being displayed. LTPO panels feature a more power efficient backplane that is able to turn individuals pixels on and off on displays, resulting in better preservation of the battery. LTPO backplane technology was originally developed by Apple itself and the company uses LTO backplanes in the Apple Watch display (Series 4, Series 5, and Series 6) - capable of scaling the refresh rate from 60Hz to 1Hz.
So how come companies like Samsung and OnePlus are using Apple’s technology before Apple brings it to its iPhone? This is becuase these companies have tweaked Apple’s tech slightly in order to use LTPO displays on their smartphones.
Currently, the OLED displays in several flagship smartphones user low-temperature polycrystalline silicon (LTPS) in the construction of thin-film-transistors (TFTs) that form the backplane of a display. However, using just LTPS doesn’t allow for a dynamic refresh rate. Hence, smartphones like the OnePlus 9 and the Samsung Galaxy S21 use extra hardware to make the refresh rate variable. The displays that claim to use LTPO backplanes are technically a combination of LTPS TFTs and transistors made of Indium Gallium Zinc Oxide (IGZO). This results in a display back panel that uses IGZO TFTs for driving the display and LTPS TFTs switch circuits. All this leads to a more power efficient display that can dynamically change its refresh rate.
Brands like Samsung and OnePlus have worked on their own display tech that imitates an LTPO but isn’t something that will drive lawsuits against them. Samsung has developed a technology called HOP, which stands for Hybrid-oxide and Polycrystaline silicon. HOP combines LTPO tech with oxide TFTs. This first appeared in the Samsung Galaxy Note 20, but with the Samsung Galaxy S21, Samsung has created an LTPO panels that can reduce the power consumption of OLED by 16 percent. OnePlus 9 Pro also seems to have had found the right balance between a fast refreshing display that adjusts itself to as less as 1Hz and goes up to 120Hz.