With the birth of AMD Mobile Ryzen 4000 and Intel’s 11th-generation Core processor platform, notebook performance has reached a new peak. In order to open a large enough gap with competing products, more products have begun to focus on the improvement of experience, such as screen panels. So, what kind of panel is a good screen?

The first choice for eye protection is DC dimming

CFan was once in “What the hell is DC dimming? This article finally explained it! “In this article, two technical solutions for controlling screen brightness, “PWM dimming” and “DC dimming”, were introduced. Among them, PWM dimming is to control the brightness by alternately flickering the screen “on → off → on → off” at a certain frequency, the light control is precise, and the picture quality control is better, but it is easy to cause eye astringency due to the flashing screen when watching for a long time. , migraines, etc. DC dimming changes the brightness by increasing or decreasing the power of the mobile phone screen. There is a defect of uneven color at low brightness, but it is more eye-friendly without the screen flickering.

Many people think that PWM dimming is only a patent for smartphones that use OLED screens. In fact, notebook screens are also mainly based on this dimming scheme, but the frequency of PWM dimming in the latter is relatively high, which is different from the low-frequency PWM commonly used in mobile phones. Compared with dimming, it is not so eye-catching.

You can open the camera app on your phone and switch to professional mode, increase the shutter speed to 1/250s or faster, look at the notebook screen, and constantly adjust the brightness of the notebook screen. If there is obvious flickering on the picture in the viewfinder, it means that the notebook screen adopts low-frequency PWM dimming under the current brightness.

This notebook uses PWM dimming at 0~99% brightness, the lower the brightness or the faster the shutter, the more obvious

It should be noted that the control strategy of some notebook screens is to use PWM dimming at 0~50% brightness, while some notebooks use PWM dimming at 0~99% brightness. At this time, the former is obviously more intimate, as long as When the brightness is higher than 50%, there is no problem of screen flicker and eye damage.

When the brightness is increased to 100%, the screen flicker disappears, indicating that it is DC dimming at this time.

In order to eliminate the problem of PWM dimming that hurts the eyes, some notebooks have even introduced the selling point of global DC dimming. If you need to deal with the notebook screen all day, it is right to choose the model with global DC dimming first. Of course, we are looking forward to the emergence of notebooks that can switch between DC dimming and PWM dimming at any time in the future, so that users can get what they need.

High color gamut is required for fuller colors

Color gamut refers to the breadth and richness of colors that a screen can display. The common color gamut standards in the notebook field are mainly NTSC based on American standard TV, sRGB based on computer operating system, DCI-P3 and AdobeRGB based on film and television. These four standards overlap each other in color gamut coverage. Slightly different.

Among them, 72% NTSC and 100% sRGB are considered a level. As long as the notebook screen meets the above high color gamut standards, it is enough for ordinary users and gamers to toss. 100% AdobeRGB can perfectly cover the CMYK color gamut used by the printer, so this high color gamut standard is more suitable for users engaged in photo printing, inkjet printing and poster design. If you are engaged in video editing, you need to look for the 100% DCI-P3 color gamut, which can help you render blockbuster movies with more color impact.

So, is a notebook screen with a high color gamut enough? The answer is naturally no, because a screen that can display more colors innately does not mean that the currently displayed color is accurate.

WYSIWYG color calibration and color correction

Except for a few notebooks that use OLED screens, the screens of most products are LCD panels + LED backlights. Due to the inherent bluish problem of LED backlights, the color accuracy of the screen is often poor when displaying blue and cyan. It requires monitor, notebook manufacturers or users to spend more energy to calibrate the color and calibrate the color displayed on the screen to infinite Close to the standard color, reduce the ΔE value represented by “color standard”.

Maybe you think the color currently displayed on the screen is “very positive”, but there may be a certain error (ie color difference) between the color and the correct performance in the industry standard. The color difference in this color accuracy is represented by “△E<><><>

Considering that 99% of consumers do not have the ability to purchase professional color calibration instruments and operate related color calibration software, for users engaged in graphic image design, it is a one-step process to choose a (notebook) screen that has undergone color calibration certification and professional calibration became inevitable. At present, the most well-known color calibration certification in the display field comes from PANTONE (Pantone). The screen display certified by PANTONE can be infinitely close to the printing color, which is a true “what you see is what you get”.

The transition is more natural thanks to the high bit depth

In addition to color gamut and color standard, there is also a parameter called “bit depth” (bit) that affects the actual display effect of the screen, which will determine the level of color. The larger the number of bits, the more levels, and the more uniform and smooth the color transition is. .

At present, the notebook screen is mainly based on a 6-bit panel, which can display 260,000 colors. Some mid-to-high-end models are equipped with 8-bit-depth panels that can display 16.7 million colors. It should be noted that the 6bit panel can simulate the bit depth of the 8bit panel through color dithering technology, but the effect is not as good as the native 8bit panel. In the field of professional monitors, 10-bit bit-depth panels are gaining popularity.

In general, native 8bit panels must have a higher high color gamut (and are easier to pass color calibration certification), but high color gamut screens can be paired with relatively low-end 6bit panels. We can view the bit depth parameters of the current notebook screen panel in “Settings → System → Display → Advanced Display Settings”.

The game is smoother, high refresh and low response

For users who like to play games, it is indispensable to have an “e-sports screen”-that is, a game book equipped with a screen with a refresh rate of 120Hz, 144Hz or 240Hz. A higher refresh rate can alleviate picture blurring and picture tearing during game play, and can also make the picture appear more coherent and smooth in other application scenarios with high-speed content changes (such as brushing Weibo). If you use a smartphone with a screen with a high refresh rate, you can know this feeling of “you can’t go back once you use it.”

It should be noted that when the resolution is the same, the screen with a higher refresh rate must increase the voltage (power consumption) in order to make the liquid crystal twist faster and reduce the response time. The reason why thin and light notebooks are never equipped with gaming screens is that they cannot stand the increase in power consumption brought by high refresh rates, and their own hardware performance is limited. The frame rate when running games is low, and it “doesn’t need” such a high refresh rate.

Careful users may have discovered that many high refresh rate gaming monitors support NVIDIA G-Sync vertical synchronization technology, but why are there few gaming laptops equipped with gaming screens that feature G-Sync? The reason is simple. To support V-Sync technology, the display needs to install an additional G-Sync chip and pay NVIDIA a license fee of about $25, which is an additional burden on the notebook.

For a notebook to support G-Sync technology, three conditions need to be met. First of all, the product must shield the nuclear display and adopt the design of direct connection between the independent display and the screen; secondly, it is equipped with a high refresh rate screen panel; finally, the screen itself needs to support variable refresh rate, and can pass eDP without G-Sync chip The software simulation of the protocol has a discount compared to the hardware G-Sync on the monitor side.

To improve the game experience, in addition to the screen supporting a higher refresh rate, the lower the response time (the default is grayscale response time), the better. At present, notebook screens are mainly IPS panels, and the response time is generally between 7ms and 30ms. The longer the response time, the longer the delay. It should be noted that the delay has nothing to do with the number of frames, it will only affect the morning and evening you see the picture, and will not affect the quality of the picture you see. The longer the delay, the feeling in the experience is that the operation is not easy to follow, the response is a bit slow, and it is not a lag in the true sense.

It is a pity that most notebooks do not mark the response time parameters of the screen, but unless you are a professional player, you generally do not feel the operation delay caused by the long screen response time. In addition, gaming screens do not represent high quality. Now 120Hz and 144Hz refresh rate screens have panel models corresponding to 6bit and 45% NTSC low color gamut. If you want to have a higher display quality in addition to smooth games, the previous article The mentioned color gamut, color level and bit depth also need to be taken into account.

There are many parameters that affect the display quality of the notebook screen, such as brightness (below 300nit can not be seen outdoors), viewing angle (IPS is better than TN), contrast (1000:1 is a threshold, the higher the contrast, the easier it is to obtain HDR and Dolby than the horizon certification), gamma value (high color whitening, too low color dim), color temperature (color temperature), light leakage (IPS screen backlight uniformity is average, light leakage is more obvious than TN screen) and so on.

How to test the screen

If you want to test the actual display effect of the screen, you need a device called a color calibration device, and the price ranges from hundreds to tens of thousands of yuan. For ordinary users, the screen can be “physically examined” through the online screen detection website. The test items include solid color, light leak test, interference test, focus, breathing effect, contrast, color level, and saturation, but this method needs to pass the naked eye. Observing changes in screen content is certainly not as accurate as hardware monitoring, but it is enough for us to judge the basic quality of a screen.

Edit: hfy

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