Apple's 120Hz refresh rate on its latest iPhones was a great technology. High refresh rates, especially for mobile displays, are one of the greatest things that has ever happened to them. They help to highlight how fast they have become. It feels better and smoother. But why took Apple so long to make this technology available for its iPhones when it launched 120Hz iPads four years back? This feature is only available on the iPhone Pro models. Apple also marketed Retina displays as Retina, which meant that the most expensive generational upgrades were only available to those who paid extra. The iPhone 13 Pro and Pro Max have LTPO tech that Apple offers. However, it has surprising drawbacks. Despite Apple's mobile 1Hz OLED panels pioneered by Apple Watch Series 4, it fails to meet the OnePlus 9 Pro's 1Hz metric. Software restrictions also mean that app developers must update their apps in order to fully take advantage of ProMotion. Which smartphone is the best for this purpose? Let's have a look.
A short history of high refresh rates
Source: Alex Dobie / Android Central
As a quick refresher (get it? A refresh rate, which is the term used for the number of times that the display is being redrawn every second, allows your eyes to see moving images. You can think of a flipbook where you make a different sketch for each page to simulate movement. High refresh rates were initially promoted by the PC industry to give competitive gamers an edge. However, high refresh rates on mobile devices would reduce the device's battery life as the additional processing power required for such feats. Apple introduced 1Hz LTPO displays to the Apple Watch. However, OnePlus is the only company with an OLED display capable of 1Hz. Apple's 2017 iPad Pro was the first to feature a 120Hz IPS LCD display. This screen allowed for a smooth Apple Pen experience, and many other apps were able to benefit from it. It's a large tablet, so many people won't notice any battery life decreases when it has a higher refresh rate. Apple's iPad OS adjusts the refresh rate based on what is on the screen. The refresh rate of the iPad Pro would drop from 24Hz to zero when there was no movement, such as when a photo was viewed in gallery. Movies would be played back at 48Hz, which is double the 24-Hz refresh rate that most movies are shot at. Other content that has movement would use 120Hz. Razer released the Razer Phone, a phone with a 120Hz refreshrate later in 2017. However, the Razer Phone suffered from poor brightness levels that made it hard to see outside. Apple introduced a new screen technology called low-temperature Polycrystalline Oxygen (or LTPO) for its Apple Watch Series 4 in fall 2018. This was just a year after the original Razer Phone. LTPO is one of many layers in a modern display that regulates the refresh rate. LTPO is compatible with many types of display technology including OLED and IPS LCD. Samsung phones beat Apple by a whole year, but Apple was first with 120Hz on the iPad. The Apple Watch didn't use LTPO for its high refresh rate. It was actually designed to allow the Apple Watch to have an always-on display without affecting battery life. LTPO also allowed Apple to reduce the refresh rate to a remarkable 1Hz. This was a great use-case because always-on displays do not typically have movement. The Note 20 Ultra was the first smartphone to use LTPO tech two years later. Samsung used its version of LTPO this time to allow variable 120Hz refresh rates for its smartphones. The phone would adjust the refresh rate according to what content was displayed on the screen, much like the iPad. Samsung added more precise scenarios to adjust the refresh rate and decreased the minimum refresh rate to 10Hz when viewing static images. OnePlus took it one step further with the OnePlus 9 Pro, which was released in mid-2021. It lowers the minimum refresh rate by 1Hz and maintains the 120Hz upper threshold for the best user experience. The touch-based variable refresh rate is not new.
Source: Andrew Myrick / Android Central
The iPhone 13 Pro Max and iPhone 13 Pro are the first Apple phones to have LTPO technology embedded in their OLED displays. Apple highlighted this touch-based method for calculation during the iPhone 13 unveiling. This raises the refresh rate up to 120Hz by touching the screen. The system will calculate how often and when to drop the refresh rate dynamically depending on what is happening on the screen once you release the button. OnePlus and Samsung use touch-based refresh rates adjustments for a while. Many articles followed the announcement with claims of innovation from Apple, apparently without considering what the rest (non-iPhone) market was doing. Many articles focused on touch-based adjustments as the key to Apple's LTPO display technology. It turned out that OnePlus and Samsung were using the same calculations in their flagship phones, which have been around for a while. OnePlus introduced a very similar technology in the OnePlus 9 Pro. In fact, they used a very similar GIF in their blog post explaining the tech back in March 2021.
It is nearly impossible to tell the difference between the iPhone 13 Pro and OnePlus 9 Pro in these GIFs. Samsung has a similar technology, which adjusts the refresh rate based upon touch and on-screen content. However, it wasn't as responsive or reliable as Apple's or OnePlus' implementations. The touch latency of the panels is a major reason for this difference. Although Samsung and OnePlus don't publish their touch latency, OnePlus did state that the OnePlus 9 Pro's panel reduces touch latency by 25-30ms compared to the previous generation. Apple, on the other hand, publishes the touch latency at each refresh rate. This includes an amazing 8ms response when the panel is running 120Hz. This is the time it takes for the display to respond to your finger. Apple does this better than anyone else. Tshaka Armstrong, our own Tshaka Armstrong had the opportunity to record these phones in slow motion. This should give you a better idea of how they look under close inspection. These videos were recorded at 120 FPS. They can be viewed at 30 FPS. This will give you an idea of how smooth the animations look when they are slowed down to 1/4 speed. Source: Tshaka / Android Central Samsung Galaxy S21 Plus vs. iPhone 13 Pro. Source: Tshaka / Android Central OnePlus 9 Pro vs. iPhone 13 Pro. Samsung Galaxy S21 Plus vs. iPhone 13 Pro. Source: Tshaka / Android Central OnePlus 9 Pro (left), vs. iPhone 13 Pro. (right). The tech is similar but Apple's ProMotion implementation looks much better than Samsung's. These subtle differences are much harder to notice when using the phones at normal speed. However, you can feel them. The iPhone 13 Pro's lower touch latency means that it feels palpably smoother compared to the competition. You'll see that Armstrong scrolls down and up the Android Central homepage with his finger more easily when you watch the clips. The OnePlus 9 Pro is a little behind, while the Samsung Galaxy S21 Plus is even more behind. This is the impact a lower touch latency could make, and it's likely the best example of Apple's ability to deliver high refresh rates at a real-world level. Apple also offers more precise intermediate refresh rates, allowing for higher and lower values. There are 10 steps between 120Hz to 10Hz or 12 possible refresh rates. Samsung provides six steps (120Hz-10Hz), while OnePlus doesn't offer all possible steps between 1Hz-120Hz. I think their GIF suggests that there are many. What OnePlus and Samsung are doing better
Source: Nick Sutrich / Android Central