The dark mode of the phone "reverses black and white" In addition to power saving, there are actually these effects

Courtesy of Visual China

On the OLED display, when a pixel is pure black, the pixel will be turned off and do not consume energy, then if the display shows a large area of black pixels, it will greatly reduce the power consumed by the display. In addition, when lying in bed at night and looking at the phone, reading white text on a black background has less stimulation to the eyes.

I don't know when it started, our chat tool gradually became WeChat. But the dark mode of WeChat updates is rarely used.

After updating WeChat to the latest version, users can turn on dark mode. After opening, the WeChat home page, chat page, discovery page, public account article page, video number page, search page, WeChat payment page, etc. will automatically turn dark.

In fact, weChat's dark mode is the same as the dark mode of mobile phones, which reduces the brightness of the screen at night and turns to white characters on a black background. Is this dark mode good or not?

In some cases, dark mode is more power efficient

What does Dark Mode do directly? Dark mode saves power on organic light-emitting diode (OLED) displays. From the perspective of battery level, in devices with OLED displays, dark mode is actually better than bright mode. This is caused by the way OLED screens work.

On the OLED display, when a pixel is pure black (deviating from a little bit), the pixel will be turned off and does not consume energy, then if the display shows a large area of black pixels, it will greatly reduce the power consumed by the display.

In other words, with an OLED display, the white text that displays the black screen is more power-efficient than the black text on the white screen. However, there is one thing to note here, only if the pixel is completely black, it will save power. If the pixels are only very dark gray or very black but not pure black pixels, there will be no power saving effect. For aesthetic reasons, many dark modes use dark gray instead of the pure black required by OLED to really save power.

How much power can Dark Mode save? In a previous test, using the official app on the OLED screen, one turned on dark mode and one did not turn on dark mode, the results showed that dark mode has a significant energy-saving effect: at 50% brightness, dark mode can save about 14% of the power compared to normal mode; when the screen brightness is 100%, dark mode can save about 60% of the power consumed by the screen compared to normal mode.

Dark Mode has some other advantages

Does dark mode have any other effects besides power saving?

When we usually lie in the bed at night and open the mobile phone App, a sentence will always pop up: Do you turn on the dark (night) mode?

Dark mode is useful in low-light environments. When lying in bed at night and looking at your phone, it is definitely better to read white text with a black background, because the screen with a white background emits more light and may be a little dazzling.

Of course, if you reduce the brightness of the screen at night and squint your eyes to look at the phone, the light entering the eyes will be reduced, and the damage to the eyes will be reduced accordingly.

In fact, Dark Mode has some other advantages. It can improve the sensitivity of some users to bright light. For example, if a person with "photophobia" has a bright background light that may cause a migraine, then the dark mode can help these people continue to use the phone. Others have vision problems and it's easier for them to read bright text on a dark background, which is why some phones had the "invert color" feature before dark mode became popular.

According to the American Optometry Association, astigmatism is a very common phenomenon. Astigmatism patients have a harder time reading "whiteboard black characters" than reading "blackboard white characters".

Although many people feel more comfortable using dark mode in dim conditions, the specific situation also varies from person to person. Humans are naturally diurnal, so most people are more accustomed to seeing black in bright light than the opposite of dark patterns.

However, whether dark mode is good or bad, there is no definite conclusion, as long as you are comfortable with it.

(Source: Institute of Physics, Chinese Academy of Sciences)

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From "big heads" to OLED

In most cases, the screen panel of a mobile phone display mainly uses two different technologies: liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs).

Before that, there was also a cathode ray picture tube display, commonly known as the "big head". In a cathode ray picture tube, the "cathode" is actually a heated filament. The heated filament is placed in a vacuum glass tube, and then the heated filament creates an electron beam. And it works by exciting the phosphor in the screen by an electron beam to display the image. Since the phosphor is extinguished quickly after being lit, the electron gun must excite these points in a cyclical manner.

LCD has been around for a long time since the late 1990s, after the replacement of displays, and has always been the main application technology for various electronic displays. Its appearance is a huge innovation in display technology, allowing us to stay away from the "big head" and embrace thin and light displays. An LCD consists of many pixels, one pixel contains three subpixels (i.e. red, green, blue, RGB). To activate a large number of subpixels, each pixel requires a thin-film transistor (TFT), which is a semiconductor device that acts as a control valve to provide the appropriate voltage to each pixel. Then through the polarization action to change the amount of light through, that is to say, in the case of unchanged light, it only relies on changing the amount of light passed to adjust the color and intensity of light, that is, a shading principle.

OLED works by streaming current through organic compounds to light up individual pixels. If we apply a potential difference between the anode and the cathode, when the current starts flowing, the cathode receives electrons from the power supply and the anode loses electrons. Electrons negatively charge the light-emitting layer (similar to n-type materials), while conductive layers are positively charged (similar to p-type materials), and holes have greater mobility than electrons, so they cross boundaries from the conductive layer to the emission layer. When a hole encounters an electron, it releases energy in the form of photons, so as long as the current is kept flowing, the OLED will produce a continuous stream of light. This principle of operation gives OLED many advantages, such as excellent contrast, more vivid color saturation, and greater efficiency.

Source: Science and Technology Daily