one plus 7 dc feature
ANDROID TECH EXPLAINED

What is DC Dimming & Why it’s Important for AMOLED Display Smartphones?

 

 

Most OLED panels use a method called Pulse scope Modulation (PWM) for dimming its brightness. this is completely different from DC dimming, which has been used by LCD panels to manage its brightness levels. Most users don’t know to differentiate between PWM dimming vs DC dimming, however, there’s a really little section of the population who are affected by the previous technique. As OLEDs trickle right down to mid-rangers and generally even budget smartphones, its user base is growing quickly. With a major increase in AMOLED consumption within the past few years, you’d usually find yourself seeing comments like this on the web

What is DC Dimming?

The most costly to lower show brightness of LCD and OLED screens is PWM (or Pulse-Width Modulation).

 

In the background of LCDs that have a backlight, PWM is converting to the backlight on and off at high frequency. this is often done at a quick pace and your eyes understand the combined impact as low brightness. for example, to realize 50% brightness, the backlight must require and off for an exact time.

Smartphone company they are using DC dimming on LCDs for years, however, it was only recently that they began to add it on AMOLED smartphones. this can be as a result of DC dimming features a huge downside. At low levels of brightness, the colors usually set out changes on OLED panels. In OLED panels, an amendment in voltage might amendment the emitted colors. So, at lower levels of voltage, the perceived quality of the smartphone show might go down automatically.

This following diagram shows how PWM dimming works.

dc dimming -singel
PWM at 50% brightness. Backlight or OLED is active for half cycle

At 100% brightness, you’ll be able to see that the sunshine is often on. after you lower the brightness to 50%, the panel alternates between on and off at equal intervals. However, after you additional lower the brightness, the screen stays off for a high time than it stays on. So, at acutely low levels of brightness, there’s a substantial flicker result.

dc-dimming multiple

Source: android developers

DC Dimming, on the opposite hand, is easy in theory and also the most blatant manner of reducing brightness. It involves reducing current or voltage through the backlight to lower the brightness.

DC Dimming, however, isn’t simple to implement for OLED screens, the sort OnePlus uses on its phones. this is often as a result of, in AMOLED displays, every picture element is power-driven one by one and reducing the voltage or current through these OLEDs additionally causes a shift in color.

Which is to mention, with DC Dimming, you’ll notice completely different colors at different brightness levels. So, OEMs resort to passing high current through OLED in forever and maneuver off periods within the PWM cycle to lower brightness.

 

DC-Dimming process
Display Brittleness Dimming on-off

This is again why OnePlus has listed Dc dimming as an optional feature in Laboratory. colors take success and therefore users who aren’t sensitive to PWM or flicker have the choice to choose.

Going by our involvement, there’s no substantial downgrade in colors even once you activate DC Dimming on OnePlus 7 pro.

Do the screens flicker less with DC dimming?

In AMOLED displays, PWM flickering sometimes shows at a frequency of regarding 200 – 250 Hz across the entire brightness range up to 99%.

The first conclusion of our measurements with the scope is that you simply will positively see a change with DC dimming. whereas with PWM while not flickering protection, the frequency varies on each the Xiaomi and OnePlus smartphones, it becomes a lot of even with DC dimming turned on. This alone would possibly already relax the eyes.

The OnePlus 7 pro operates even a lot of cleanly here. At 50% brightness, there’s no flickering any longer, which only happens at terribly low brightness levels. within the Xiaomi Black Shark 2 on the opposite hand, the flickering frequency of 60 Hz is visible up to the most brightness.

Another positive purpose is that the reaction times of the show aren’t negatively impacted by DC dimming per our measurements.

OnePlus 7 Pro (0% brightness)
PWM OnePlus 7 Pro (0% brightness)
OnePlus 7 Pro (50% brightness)
DC Dimming OnePlus 7 Pro (50% brightness)

List of AMOLED display phones that support DC Dimming?

  • OnePlus 7 Pro
  • Black Shark 2
  • Redmi K20 Pro and Redmi K20
  • Xiaomi Mi 8
  • Xiaomi Mi 9
  • Oppo Reno 10X Zoom

How to enable DC Dimming on OnePlus phones

The option is present on the one plus 7pro.you’ll activate DC dimming right before already dark usage and switch it off later.

Step 1: Open the setting scroll down to Utilities.

stting

Step 2: Now tap on OnePlus laboratory and turn on DC Dimming.

What’s so bad about PWM Dimming and its flickering?

Usually, even at low brightness levels, the common human eye won’t be able to see the flicker from PWM dimming. however, that doesn’t mean it won’t affect you in any method. Some people are also sensitive to the current flicker. And in these peoples, PWM dimming will cause eye strain, headaches, and migraines if exposed for long periods. this can once true when the ambient lighting is low.