What is the mainstream screen type of LCD liquid crystal display?
Sinocrystal would like to make a brief introduction to the production plant of LCD.
Regarding LCD and OLED, as mentioned at the beginning of the previous article, the current mainstream screens can be attributed to two categories: LCD and OLED. Let’s talk about AMOLED screen
Here we will discuss the difference between LCD and OLED.
(1) IPS hard screen
First of all, IPS screen is an extension of LCD. The most famous mobile phones using IPS(ips lcd) are iPhone 4/4s and iPad 1~3 generations. From
This is also enough to see that although the LCD screen is not as good as OLED in terms of technical and theoretical performance, it has not declined.
Relatively speaking, IPS is more purely a panel. The difference between him and the traditional VA soft panel is that due to the unique horizontal division of the IPS hard display.
The sub-structure makes it free of water streaks, shadows and flashes when touching, and it is very stable, so IPS is a real hard structure, especially in dynamic
The performance of the game is relatively good. The technical principle of IPS determines that it can provide faster response speed and light leakage when the screen is under pressure
It is smaller than VA LCD, so it is more suitable for making touch screen.
The defects of the early LCD are relatively clear. For example, the viewing angle is very poor. If you look at it from the side, the whole color is wrong. these original
The problem is that in the efforts of many technology manufacturers to improve the structure or molecular structure of the original LCD, the display effect can be improved.
And some mainstream display effects catch up with or even surpass the current technology of OLED, which is still not mature enough, IPS is one of them. IPS hard screen panel
The viewing angle can reach 178 degrees. The degree of color change when viewed from the front and viewed from different angles is called the color distortion rate.
The value is almost indistinguishable with the naked eye, which means that the effect of viewing the picture from the front or the side is the same.
Hitachi was the first to develop an IPS panel, while LG Display’s IPS has undergone several generations of development.
Different from traditional IPS, some of the technologies involve Hydis’s FFS wide viewing angle technology, which features: low power consumption, high light transmittance, high brightness
High speed, fast response, no color cast, high color reproduction and other characteristics. According to the hands-on results of foreign dismantling and repair site iFixit, the new iPad adopts
Display provided by Samsung.
Some devices that are not so well-known in the publicity point also use IPS, such as Amazon’s Kindle Fire, HP’s TouchPad. But he
They still have some differences in display and performance, which are related to different manufacturers and different generations of products.
(2) TFT and SuperLCD
Both are LCD screens.
TFT has basically been expelled from the stage of history. In 2011, only moto was still keen to produce mobile phones with TFT screens. So at that time,
Torola’s mobile phones generally have poor screen performance, whether it’s color performance, contrast ratio, etc. And the viewing angle performance is also the same as the current
Mainstream screens are a far cry. The moto defy+, which is still active on the market, uses this kind of screen.
TFT is the prototype of almost all current LCD screen technology improvements, so the earliest generation of IPS is also called Super TFT.
Super LCD is an advanced extension of LCD. At present, because HTC is very keen on this screen, Super LCD can be regarded as blooming.
Since HTC Desire, SLCD has grown at a very fast rate. Personally, I prefer SLCD screens because of their color performance and viewing angle.
In terms of degree, it is closer to the display effect of the OLED screen, and the color reproduction is more realistic, and there is no sign of overdoing it.
SLCD was originally a screen jointly developed by Sony and Samsung. Later, Sony withdrew from the entire line and was made by the Samsung family. This abbreviation for SLCD
The weak use of Samsung’s full spelling method can be Super Clear LCD.
It should be noted that the screen used in the latest HTC One X mobile phone lock is called the second generation of Super LCD, which is called by HTC.
The display of the Super LCD 2 is excellent, and the glass on the surface of the HTC One X is crystal clear. However, this screen
The fact is that AH-IPS.LG has taken the name AH-IPS as its own, and is not allowed to use it by other manufacturers. Its specific details are unknown and need to be further verified
, AH-IPS is a new generation of IPS panels launched by LG in the first half of last year. Some experts observed the pixel arrangement of the HTC One X screen under the microscope
, the same as LG’s Optimus 4X HD, they believe, just the name difference, and the AH-IPS is the same screen.
(3) AMOLED
The biggest difference between LCD and OLED is that the pixels of LCD do not emit light (the so-called pixels, which have been mentioned above, can be understood as being close to the screen.
The small particles and small squares on the screen that you see during the screen). The reason why we can see the display content of the LCD screen is that it is illuminated by an external light source.
Bright (eg LED backlight and external natural light). This is similar to, we have a red table in our house, you can turn on the light during the day or at night.
to see it and know it’s red. But if it’s night and the lights are turned off, can you still see? Of course it can’t be seen, because this
A table itself does not emit light
On the other hand, the pixels of OLED can emit light by themselves, and do not need external light source to illuminate, just like a table that can light up by itself. It is generally believed that OLEDs are
Technologically more advanced than LCD, but because it is still immature, and cost issues, LCD still glows and heats up in modern screens. OLED can be like
There are two main advantages of self-illumination. The first is that the brightness will be better than that of an LCD illuminated by an external light source. The second and most important point is that
, because the pixels of the OLED screen are self-illuminating, and each pixel can freely control whether to emit light or not, so the OLED screen is showing the color of black
When the black part is black, the pixels in the black part can not emit light at all, so the black displayed is the real black, and the black is deeper and purer.
It also improves the overall contrast performance of the screen.
—— Since the LCD itself does not emit light, even when it is black, the external light source will still illuminate the entire screen, and the black part is no exception
, so the black will appear whitish. – With this feature, OLED is more power efficient when displaying a black screen (especially for Windows
This is especially true for systems such as the Phone 7 that use black as the main color).
I have written articles on screen materials in the past, but this time I want to talk about some points of AMOLED in relative detail.
AMOLED screens are OLEDs, which are different from the other screens mentioned above. So it is technically more advanced. and
AMOLED technology is all in the hands of Samsung, and this screen is also an ace in Samsung’s hands. It can even be considered that Samsung mobile phones are different from other
A logo of a mobile phone (although different brands of mobile phones have adopted this screen one after another). He has those advantages of OLED mentioned above.
It is impossible to feel empty talk. Many people who do not see many screens feel that: the screen is not always like that, how can it be excellent no matter how good it is.
In the early days, I also thought about it. Later, after comparing, I found that there are several orders of magnitude difference between the screen and the level of the screen.
Just talking about this item in the strong sunlight in summer, although the current mobile phone screen is mainly as clear as the sun, no matter what kind of screen it is.
or display technology. But the reality is often more skinny than the ideal. I’m used to seeing all kinds of screens, and the one I’ve used the longest is SLCD.
Although SLCD’s better models are very good in color performance, they are not worse than AMOLED. But once in the sun, everything becomes a floating
cloud. Whether it uses LG’s NOVA display technology or Sony’s White Magic (the display technology used in the latest Xperia series), simply
Still LCD screens (except for iPhone), they become extremely tragic in sunlight, normal sunlight, look carefully, pay attention to the angle, barely
It can be seen clearly. If the sun is shining, if you plan to take pictures, it may be very difficult.
Under strong light, it is not so difficult to still see, only the AMOLED screen and the iPhone 4/4s with IPS are left. Relatively speaking, AMOLED screen
better. But at this time, it was only visible.
A. Pentile sub-pixel arrangement
One thing that many people misunderstand about AMOLED is that, as seen by the Samsung Galaxy S, AMOLED screens have a much harsher graininess than usual screens, and the screen
The small particles on the screen are distinct, and the same is true for the Nexus S. When we first met, Samsung fans ignored this flaw and
The heart boldly declares: Whoever looks at the screen will put his eyes on the screen, you Samsung black save it. ——But it turns out that it is not allowed to get close to the screen
the screen, the graininess of the text is already quite clear. However, this graininess problem is not a problem with the AMOLED screen itself.
Unlike the screen in the LCD era, since the pixels of the AMOLED screen emit light by themselves, adding pixels to the screen means increasing the resolution.
Directly increases the cost of the screen. The cost of increasing the resolution of the LCD screen is almost negligible in this regard (except for some technical
means). Taking this cost into consideration, Samsung has made some technical modifications to the AMOLED screen.
Each pixel (that is, each small particle) of a traditional screen is composed of three sub pixels, namely R (Red), G
(Green), B (Blue). The harmony of these three subpixels allows a single pixel to form a variety of colors (which can be easily understood as such). Such as
The image below shows the letter A in white.
For AMOLED screens, the increase in screen cost caused by adding pixels is a headache, so this sub-pixel arrangement has been adopted.
to readjust. The sub-pixels of the first-generation AMOLED screen have been reduced from 3 sub-pixels per pixel to 2 sub-pixels per pixel.
In this way, the cost will naturally come down. ——So if there are only two sub-pixels, how can we express multiple colors? – So, solve
The method is that if the pixel in this grid has only two sub-pixels R (red) and G (green), in order to display white, B (blue) sub-pixels are needed, borrow
The blue subpixels of the neighbors are shown, this subpixel arrangement is affectionately known as the Pentile arrangement, as shown in the following figure.
For the arrangement of Pentile sub-pixels, it is not as easy as we think technically, and he still needs to solve some practical problems. E.g
Sometimes he can’t borrow the sub-pixels of adjacent pixels (because the adjacent pixels may need to display black and not emit light). In addition, we
It can also be seen in the above figure that there are relatively large R and B sub-pixels on the left side of the Pentile arrangement, which is easy to cause color borders of text on the screen display.
Phenomenon.
Even after all these technical problems are solved, the most terrifying thing is that the text display effect is extremely bad as mentioned above. same size for the same resolution
For small screens, the screen with Pentile sub-pixel arrangement is better than the screen with traditional RGB sub-pixel arrangement.
Feel much stronger. This is the crux of the grainy text on phones like the Galaxy S.
However, it seems that many people don’t care about this graininess at all, and many sensitive people can’t accept this sub-pixel arrangement at all.
The first and second generation AMOLED screens, that is, AMOLED and Super AMOLED, all adopt the Pentile sub-pixel arrangement. their generation
Table models are: NOKIA Lumia800, Samsung Galaxy S, Nexus S, Ominia 7.
In addition, HD Super AMOLED, a derivative of the AMOLED high-resolution screen, also adopts the Pentile arrangement, and the representative model is the Galaxy S that has just been launched.
III, as well as the Galaxy Nexus, Galaxy Note, and more. The improvement of resolution and pixel density can alleviate this sub-pixel arrangement to a certain extent.
Columns bring about the problem of grainy text display.
There are other derivatives of AMOLED, such as the Super AMOLED Advanced used by moto’s Razr, which also uses a Pentile arrangement
.
B. Super AMOLED Plus
It is often referred to as SAP screen, which can be considered as the third generation of AMOLED screen development. Relatively speaking, the improvement of Plus to the second generation is mainly about
Instead of using the Pentile sub-pixel arrangement, it is changed to traditional RGB to make the text display look more delicate. – Samsung here
In the promotion of the AMOLED screen, one of the propaganda points is that the text display is more delicate, but in fact, this is just to make up for the previous problem.
At present, it seems that mobile phones with SAP screens are still rare, which may be caused by the unsatisfactory cost control. The representative model is the Galaxy S II.
C. Some inherent flaws of AMOLED screens
In terms of display effect, contrast, performance in sunlight, black performance, viewing angle and many other aspects, AMOLED screens are the best at present.
Screen. Putting aside the issue of Pentile sub-pixel arrangement, AMOLED still has some flaws that have to be discussed.
i. Burn-in problem: The characteristic of the OLED screen is that each pixel emits light by itself, and the pixels in the black part do not emit light. performance in different colors
On the above, there are differences in the harmony and luminescence of pixels, to give a simple example. Plasma TVs in the past had this problem. If you watch a certain TV for a long time,
If you are a TV station, then the pixels in the logo part of the TV station will not change for a long time. As a result, if you change to another station later, the position of the logo can still be used.
I faintly see the shape of the logo of the TV station I’ve been watching. ——In the mobile phone, such as the ANdroid system, the status bar is not moving for a long time, he
Displays information such as battery power, mobile phone signal, time, etc. After a long time, you can let the mobile phone display a solid color picture in full screen, and it will
There is a faint trace of the information left in the position of the previous status bar.
The root cause of this problem is the self-illumination of OLED pixels. Due to the differences in the display of each pixel on the screen, the aging speed of each position is different.
In particular, the difference in pixel aging is obvious offside, and this phenomenon of afterimage is a complete physical damage and cannot be recovered.