This year, smartphone display panels with variable refresh rates as low as 1Hz have been made available. Which means the screen can draw a new image once every second and consume much less battery.

Previously, smartphones with always-on displays featured 60-120Hz refresh rates. Which would fluctuate between 10-120Hz depending on the task.

But this wasn’t acceptable for Apple, who wanted their always-on display to have virtually no negative effect on battery life. So they waited for displays with refresh rates of just 1Hz.

Apple has also been developing a dual TFT circuit similar to the Apple Watch that turn pixels on and off for individual frames every fraction of a second.

These technologies are estimated to make the upcoming iPhone’s always-on display 5-15 percent more power efficient. And that’s exactly Apple took their time.