AMOLED, TFT-LCD screen difference

First, let’s talk about the AMOLED and TFT-LCD’s light principle. See below:

AMOLED, TFT-LCD screen difference (1)

Seen from the figure, the TFT-through the LCD Backlight (backlight unit) light, open and close control through the liquid crystal, and then through various RGB color filters, display different colors. AMOLED is self-luminous, through RGB phosphor display different combinations to display different colors.

Due to the different light way, TFT-LCD backlight is required, naturally overall thickness thicker than the AMOLED.

AMOLED, TFT-LCD screen difference (2)

This is Zhanglao diagram, although the last two years by TFT-LCD In-cell and other techniques to reduce the overall thickness of the belt touch, but in general, AMOLED or TFT-LCD than thin.

But also because AMOLED is self-luminous, it can not be the same as the TFT-LCD, liquid crystal is injected into the glass, but to the light-emitting material is injected into the AMOLED AMOLED vapor deposition or by printing way.

Printing way still in development stage. Including Samsung are currently used in the form of vapor production.

Samsung to make AMOLED deposition yield enhancement, using a variety of PenTile to produce.

AMOLED, TFT-LCD screen difference (3)

Why PenTile can increase yields? For example, FHD resolution of 1920×1080, with PenTile only need to make a resolution of 1920×720, you can allow the user to see the effect of 1920×1080.

But after all the expense of some of the pixels in a special pattern, there will be distortions in the display problem, but that is a natural image, man took the picture, not normally found in this type of distortion.

Many people at the time to promote its AMOLED and AMOLED is propaganda than TFT-LCD power, but Zhongguancun Online has done a test, the conclusion: for AMOLED and IPS by two different materials tested, although for subdivision the calculation is not the same, but we can clearly see that the most energy efficient AMOLED display when black, followed by green, white color is the most power-hungry.

On the other hand, the use of IPS screen long model three colors show no material impact on power consumption.

Thus we can see that the use of a dark background or on the desktop allows mobile phone can save a point for the AMOLED screen is indeed feasible, and the effect is really obvious, but for the IPS screen, the display because of the structure and mode (using a backlight ), using the background dark lines more power does not hold.

When it comes to the brightness dimmed, AMOLED color yellow is also a problem. But over the years, the evolution of technology AMOLED, the problem is also improved slightly.

As for the AMOLED market, due to the AMOLED thinner, although the price of your AMOLED or many mobile phone manufacturers want to choose AMOLED. Just two years ago because of Samsung’s own Galaxy series of great sales, reducing the supply of domestic brand mobile phone manufacturers, leading domestic manufacturers can not use. But in recent years the growth slow Samsung’s own mobile phone, and its AMOLED production capacity, since last year, reducing the AMOLED prices, making use of AMOLED brand mobile phones more and more.

In addition to Samsung, LG, Sony, domestic manufacturers have gradually started AMOLED, Shanghai and Hui, Kunshan country was, BOE, Tianma have started AMOLED, which makes AMOLED prices gradually decline.

Of course, the future is bright AMOLED, which is the main reason for the suppliers started the AMOLED. AMOLED in the future may be to focus on three directions:

1, a flexible display

This is AMOLED and TFT-LCD compared to a big advantage. After all, self-luminous, like a layer of TFT-LCD backlight, the TFT-LCD can not be made flexible.

2, print production

With printing allows AMOLED become thinner and easier to do curved screens. But the printing technology is not mature, there were only TCL in researching this technology.

3, VR

With virtual reality gradually rise, the domestic manufacturers are doing virtual reality also increased again. But I often hear those who have indicated to me that experience: he put on foreign manufacturers such as Oculus, Sony and Valve’s VR head was when the experience is very good, but the head was put on domestic VR, when fixed okay a move will make extreme vertigo, which is why? According to the general opinion, VR head was simply worn on the head of the display, motion (Motion Sickness) in the end is how is it?

Now I use a few schematic presentation.

AMOLED, TFT-LCD screen difference (4)

We can see this picture on the left is the real world, an object moving from left to right eye sees the situation: With the passage of time, the trajectory of the object is a line; and the right plan is any species display out: the image of an object at a point after each show for some time, skip to the next point; it is not a continuous motion.

But as soon as the person’s head movement, the human eye will be displayed relative to the object relative motion, then in the eyes of the trajectory of the object becomes a different way:

AMOLED, TFT-LCD screen difference (5)

Turn left when right in the head, the trajectory of the original object becomes a stationary right like this, it is no longer a point, but at the end of each frame, it jumps back to “should” in s position. However, the human eye’s persistence of vision phenomenon will be retained on a frame and the image, so the image will cause streaking, causing dizziness.

At this time in order to avoid dizziness, there are two ways:

1, if we still assume 60hz refresh rate, head rotation speed of 120 degrees / sec, then a rotation of the head frame of 2 degrees to DK2 resolution, a frame delay of 19 pixels, this time head display image display will be rather vague. The higher the resolution, the more serious the problem.

In the theoretical limit of resolution of the human eye to calculate a frame delay will reach 600 pixels. From 60 to 90, to 120, to 200 …… might finally to 1000hz, when our visual system completely not tell the real or virtual.

But obviously we can not increase the refresh rate to 1000hz, currently Oculus Rift CV1 and HTC Vive using 90hz refresh rate, while Sony Project Morpheus uses a 120hz refresh rate.

2, is to reduce afterglow (Persistence).

Twilight (Persistence) is a concept in the CRT display period. CRT monitors are excited by electron beam emitting phosphors on the screen, so this is actually a CRT display only a short period of time of the pixels within each frame is light, and the rest of the pixel is dark, the diagram is as follows:

 

AMOLED, TFT-LCD screen difference (6)

You can see the liquid crystal display, each pixel frame is always light, so the liquid crystal display was called “full afterglow” (Full Persistence) display.

AMOLED, TFT-LCD screen difference (7)

Intermediate This figure only half the time for lighting pixels; and the right of this picture is in the ideal case only a very short time the screen light, which is “zero afterglow” (Zero Persistence). Since the human eye’s persistence of vision effect, the refresh rate is high is sufficient not notice the screen is only a very short time frame of each light. But in order to make up for the lack of brightness, luminous intensity of the pixels within each frame to be greatly enhanced.

Low afterglow display the VR head was the significance of that head movement trajectory when the trajectory of objects closer to the real physical world:

AMOLED, TFT-LCD screen difference (8)

Then head movement to bring smear will be greatly reduced. Assume that the same rotation of the head 120 degrees / sec, was first refresh rate 60hz, a luminescent screen frame 2ms, resolution and viewing angle to DK2 meter, then in the arc of rotation of the head of the human eye 2ms observed visual delay only 2 pixels, vertigo just gone.

But we all know the basic principles of the LCD display: LCD flip by making selectively permeable to light. This means that the LCD display is difficult to use low afterglow.

AMOLED, TFT-LCD screen difference (10)

 

Flip LCD response time is also the fastest 2-4ms, but also led to the principle backlight LCD can not do all black. In contrast traditional CRT monitors are natural low afterglow display.

Want to solve this problem, VR head was self-luminous display must be used, for example, OLED. Since each pixel is its self-luminous, so OLED screen can achieve low afterglow.

3 Comments

  1. very good

  2. Verna
    07/27/2016

    very good

  3. Louie Kibbler
    08/29/2016

    I ll never buy a device with amoled, bad experience with burn in. So I decided to choose lcd because of the lifespan. just replaced my year and a half old S4 with a V10. I was surprised to see the whites on the S4 were yellowish compared to a vibrant white on the V10.

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