Some time ago, Tianma microelectronics officially released the world’s first LCD multi-point fingerprint identification scheme (Ted finger print, referred to as TFP), which integrates the identification module into the LCD panel, so it is called on-screen fingerprint. TFP supports fingerprint identification in any area of the full screen. Users can not only unlock blindly, but also customize fingerprint control and app encryption to enhance security and privacy.

As soon as the fingerprint on Tianma’s LCD screen was released, the users who once called “LCD will never be a slave” were excited. After all, the LCD party and the OLED party have been fighting for many years. Now, can the fingerprint on the screen, which seems more convenient than the fingerprint on the OLED screen, pull back the LCD? Can LCD return to the original “golden age”? Let’s talk about it slowly.

01 years of LCD weakness from “screen fingerprint”

When the fingerprint scheme of LCD screen is not released, “fingerprint unlocking method” even becomes a method to distinguish LCD screen from OLED screen. Although the LCD party said that the screen fingerprint unlocking scheme is not as convenient as the back and side fingerprints, it either does not support it or does not support it. In this war without gunpowder, the LCD party suffered a disastrous defeat.

Today, TFP brought by Tianma supports fingerprint identification at any position on the screen. Will it be able to turn over in the “fingerprint identification” war? Not necessarily. The TFP scheme brought by Tianma can really make the process of fingerprint identification more free than the fixed-point unlocking of several fingerprint unlocking schemes on OLED screen, which is a pull back to a certain extent.

Choosing to put fingerprint identification module on the screen is the choice of comprehensive screen era. Time to dial back, in that era when the mobile phone still had a “gorgeous” chin, the combination of the fingerprint of the mobile phone and the “home” key was actually quite convenient. When you press the power key, you can unlock it at the same time. Convenience is achieved, but “not beautiful enough.”.

Therefore, when the mobile phone enters the era of full screen, in order to pursue a higher screen share, moving the fingerprint module to a suitable location has become a big problem.

From the perspective of ergonomics, back fingerprint is also a good solution, but it can’t stand ugly. In the transformation period at that time, the side fingerprint had to sacrifice the thickness of the fuselage for technical reasons. In the final analysis, it was still a word – “ugly”.

Back fingerprint identification

So, when the fingerprint appeared on the screen, I seemed to be Tang Bohu who saw the “fragrance of autumn” against the background of “fragrance of spring, summer and winter”. There was no more language to describe it, only a “real fragrance”.

“Qiuxiang” can be said to be both talented and beautiful, not only in the face value hanging play several other solutions, but also in line with the user’s habits. The contrast is so obvious, isn’t it clear who to choose? As a result, LCD, which was difficult to achieve screen fingerprint at that time, was forced to stand aside for several years.

Can 02 screen fingerprint help LCD return to glory? hard

At present, the commercial screen fingerprint identification technology mainly has two schools, optical scheme and ultrasonic scheme. The optical scheme mainly relies on the light reflection to detect the fingerprint circuit, which needs the structure to be thin enough and without backlight interference, so OLED screen is inherently suitable for screen fingerprint identification.

Tianma microelectronics released LCD fingerprint identification scheme, can LCD return to the original "golden age"?

Optical fingerprint identification

On the way forward of LCD screen fingerprint identification technology, there are mainly two difficulties: poor penetration and backlight interference. Previously, TCL Huaxing used infrared light to replace the reflection of visible light on the finger for imaging, and used infrared transmitters, fingerprint receivers, and various optical coatings to improve the transmittance and imaging accuracy, but the results were not ideal – the recognition rate was 100%

Tianma’s solution is an upgraded version of the current optical screen fingerprint recognition, which integrates the recognition module in the liquid crystal panel, converts the image sensing scheme of CMOS into the thin film transistor (TFT) array scheme, and adds a layer of a-Si (amorphous silicon) driven sensor (photoelectric conversion diode) by using the TFT process.

This kind of design makes the infrared ray of the recognition module need not pass through the liquid crystal display, which really helps to improve the recognition rate and speed. However, whether it can achieve the two recognition methods of OLED with relatively mature technology remains to be discussed. In addition, such a design process requires high sensitivity, which will eventually improve the quantum efficiency of TFT sensor, but it will also lead to yield reduction and cost increase.

From the design point of view, TFP technology brought by Tianma is not mature enough at present. It still has a long way to go to catch up with OLED which has been in commercial use for several years. It is a distant topic to talk about “turning over the market with on-screen fingerprint technology”.

03 once brilliant LCD was left behind, where did it lose?

From the screen itself, LCD and olcd have their own advantages and disadvantages

1. LCD screen: with LCD layer, the overall structure is relatively thick; it can’t be bent; it can’t self light, the color is cold, but there is no risk of screen burning; the cost is low;

2. OLED screen: no liquid crystal layer, the overall structure is relatively thin; it can be bent or even folded; it can be self luminous, the overall color is very uniform and saturated, the visual effect is better, but it may “burn”; the cost is higher.

Tianma microelectronics released LCD fingerprint identification scheme, can LCD return to the original "golden age"?

In this way, the two kinds of screens are playing back and forth. It seems that LCD should not be left behind by high-end flagship so soon. But why is it difficult to see LCD screen in flagship models now? Instead, it is widely used in middle and low-end models? To a large extent, the failure of LCD is not due to the technology, but the rival OLED has tied the terminal manufacturers to their own chariots.

There is a very important time point when the mainstream of the market changes from LCD to OLED screen. In 2017, the appearance of screen fingerprint technology has attracted much attention of OLED, and apple, which insists on LCD, has also replaced OLED in iPhone X. Before that, LCD was the absolute mainstream, but after that, LCD was labeled as “low-end, outdated, power consumption, poor display effect, and can’t use fingerprint under screen”.

IPhone x screen

Throughout the current new products, high-end models collectively turn to OLED screens, including Xiaomi, vivo, Yijia, oppo, Meizu and other manufacturers, and almost take their own customized AMOLED with Samsung as an important selling point.

In addition to the terminal manufacturers, the actions of the head screen suppliers have long revealed the fact that the LCD market has gone. At the beginning of this year, Samsung display group said it would shut down all its LCD panel production lines in South Korea and China by the end of this year and give up LCD production completely. In fact, Samsung is the slowest – Panasonic and LG display announced the phasing out of LCD production as early as last year. The departure of the head supply chain also basically means that LCD has been basically abandoned in the industry.

In addition, OLED has more characteristics that can attract consumers and become the selling point of high-end flagship, which also makes terminal manufacturers prefer OLED screens.

For example, the flexible and foldable properties of OLED make LCD in an awkward situation in this era when “curved screen”, “waterfall screen” and “foldable screen” become the keywords of flagship aircraft.

OLED also has the characteristic of non luminous in black state, which can achieve “pure black”, but the existence of LCD backlight panel obviously can’t. As shown in the figure below, I believe many people fall in love with OLED screen because of this feature.

The self luminous characteristics of OLED can also achieve the purpose of power saving, and the power consumption is more power saving than that of LCD. According to this feature, many mobile phone manufacturers have brought the “off screen display” function, so they have another selling point relying on the OLED screen, and the LCD can only get out of the market.

Of course, LCD also has advantages, such as more eye protection. In order to prolong the material life of OLED screen, PWM dimming is generally used. The brightness of the screen is adjusted by power on and power off. The low-frequency screen flicker makes people feel dizzy under the condition of low brightness. The LCD has a backlight panel, which can change the brightness through DC dimming. There is no serious screen flicker feeling of PWM.

However, many people insist on LCD because the imaging effect of LCD is better. The pixel arrangement of RGB can ensure the comprehensive display of sub-pixel and the natural imaging picture. However, several pixel arrangements of OLED are two kinds of pixels, which can only be imaged with the help of adjacent pixels, and the image has color edge sawtooth. To reduce this gap, OLED screens have to pile up pixels – 2K OLED screens can compete with 1080p LCD screens.

If you want to feel the gap, you can see the following figure:

Tianma microelectronics released LCD fingerprint identification scheme, can LCD return to the original "golden age"?

To sum up, the fact that LCD has been pushed out of the high-end ranks is the result of many factors in parallel. Because of these conditions, it is difficult for LCD to turn over with a “fingerprint on screen”.

Finally, let’s say:

Because of its own limitations, it seems hopeless for LCD to return to the high end. The saying “LCD will never be a slave” seems to be history. Moreover, with the cost reduction of OLED screen, it is not only used in high-end flagship models, but also used in many low-end products.

Now, what LCD may lose is not only the high-end field, but also the gradual withdrawal from the stage of history. Perhaps in the future, LCD will become a memory in the history of mobile terminals.

Editor in charge ajx

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