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    2021-10-21 17:41:37
    What is AMOLED?


    Ⅰ Introduction
    Ⅱ AMOLED working principle
    Ⅲ AMOLED advantages and disadvantages
    Ⅳ The difference between AMOLED and OLED
    Ⅴ Why do smartphones use AMOLED?
    Ⅵ Is the AMOLED screen bad for the eyes?

    Ⅰ Introduction

    AMOLED (Active Matrix Organic Light Emitting Diode) is an active-matrix organic light-emitting diode panel. It is called a next-generation display technology. Samsung Electronics, Samsung SDI, LG, and Philips are all developing this new display technology. The AMOLED display consists of a pixel integrated or deposited from the thin film transistor (TFT) array. OLED technology is basically an LED using the organic compounds as an emission electroluminescent layer. Such organic compounds use current to pass through the light generated. Compared to the traditional LCD panel, AMOLED has the characteristics of faster reaction speed, higher contrast, and wide viewing angle.

    AMOLED display.png

    AMOLED display

    The TFT actively maintains a pixel state when processing other pixels. AMOLED shows the pre-storage or integrated light emitted by the OLED matrix molecular electric power, as a switch to control the current flow direction flow to each pixel. TFT backplane technology is the key to manufacturing an AMOLED display. Today, two main TFT backplane technologies, namely polysilicon and amorphous silicon, have been applied to AMOLED. These techniques contribute to the manufacture of active matrix backplanes of the flexible plastic substrate. The flexible plastic substrate is the key to producing flexible AMOLED displays.

    Ⅱ AMOLED working principle

    AMOLED drives the light-emitting diodes through a driving circuit, which minimizes the number of control circuits and enables it to have low energy consumption, high resolution, fast response, and other excellent photoelectric characteristics. Therefore, AMOLED has gradually become the mainstream technology of OLED display.

    AMOLED structure.png

    AMOLED structure

    AMOLED is an active matrix organic light-emitting diode. AMOLED screens have derived many different versions during the development process, such as AMOLED, SuperAMOLED, SuperAMOLEDPlus, SuperAMOLEDAdvanced, and so on.

    The structure of the AMOLED screen has three layers, AMOLED screen + TouchScreenPanel (touch screen panel) + outer protective glass. AMOLED is a kind of OLED technology, which represents a self-luminous display that uses multiple layers of organic compounds to achieve independent R, G, B three-color light.

    AMOLED does not have a striped anode and cathode. The anode and cathode are the whole layers. But its special is that there is an extra layer of thin-film transistor array between the cathode and the screen. This layer of TFTA determines which pixel above is bright or not bright. Because TFTA consumes less energy than the external circuit of PMOLED and has a faster rate of color change reaction.

    Ⅲ AMOLED advantages and disadvantages

    Advantages of AMOLED:

    LCD and AMOLED.jpg

    LCD and AMOLED

    (1) Compare to the traditional LCD, the AMOLED screen is very thin, and it can integrate touch layers in the screens.

    (2) AMOLED self-illuminating, a single-pixel does not work when black is displayed, and the short power consumption is displayed. Therefore, AMOLED saves power under dark and has a few hundred times of contrast, and will not leak.

    (3) AMOLED has a certain flexibility, which is not easily damaged than the LCD screen of the glass substrate.

    (4) AMOLED and SUPER AMOLED color gamut are very wide (but severe bias).

    Disadvantages of AMOLED:

    (1) AMOLED uses Pentile pixel arrangement, the actual resolution can only reach two-thirds of the nominal, and the particle feels are very heavy in the case of lower DPI. All the boundaries of color blocks such as the text, the table, and graphics need to be adjacent to pixels to assist in luminescence, resulting in serious inevitable problems such as marginality, with variegation.

    (2) AMOLED emphasizes green, causing its too bright effect. We may feel fatigued after watching a long time. The color temperature of AMOLD has a problem.

    Ⅳ The difference between AMOLED and OLED

    AMOLED is OLED, but it is not in turn. Simply put is that OLED technology includes PMOLED and AMOLED, PMOLED does not require a TFT backplane (different from the backplane of the liquid crystal), but the size cannot be done; the AMOLED size can be done. PMOLED mainly exists on early dual-screen phones and small external screens. Current mobile phones and TVs mostly use AMOLED technology.

    OLED is an organic light-emitting diode, and its luminescent material is an organic light-emitting material, which is relative to the LED luminescent diode. OLD will shine as long as the correct voltage is plus correct.

    AMOLED works when signals and supply point sources are added, allowing the diode to achieve the working state. It will light or shut down only when light or unlighted signals are given. It's not inappropriate to say that its work is like a TV set: you gave it a wired signal, but I can't see it. Only if I gave electricity. 

    PMOLED and AMOLED.png


    The OLED also has a PMOLED "passive distance organic light-emitting diode board." One is active illuminating control, one is passive illumination control. Our mobile phone generally refers to AMOLED. The so-called OLED is applied to a glass substrate on the screen (this material is very expensive), and the AMOLED is to add AM technology on the OLED panel and actively control.

    Compared with PMOLED, AMOLED has the advantages of the low driving voltage, long life of light-emitting elements. Its disadvantages are higher cost and complicated manufacturing process. AMOLED is suitable for large display screens & fast refresh rates screens, such as computer monitors, large screen TVs, electronic signals, or billboards. The advantage of PMOLED is that it has a simple structure and can effectively reduce manufacturing costs. The disadvantage is that the external circuit has a high driving voltage and is not suitable for application on large-size and high-resolution panels. PMOLED is suitable for text, icon display, small screen (2-3 inches diagonal).

    Ⅴ Why do smartphones use AMOLED?

    In general, OLED is divided into two types: active matrices (AMOLED), and passive matrices(PMOLED). PMOLED has the advantages of power saving, but the reaction is slow. These characteristics are suitable for lighting applications. Because the reaction of AMOLED is fast, it is very suitable for the display device, which is considered to be a non-two selection of the liquid crystal panel in the future.

    As compared with the traditional LCD panel, the color gamut of AMOLED is wider, and the NTSC color gamut is up to 100%; the oppost is more than ten times the current TN panel; the perspective is wide, even 180 degrees. And because there is no backlight, it is easy to drive, etc...  The advantages of high resolution and power saving are more suitable for applications in small handheld devices. The only drawback is that the current price is too high for adoption; although panel manufacturers such as SAMSUNG and LG have released large-size panels for TVs and computer monitors, they have not yet been mass-produced due to their low output and high technical difficulties.

    Ⅵ Is the AMOLED screen bad for the eyes?

    The published flagship phone almost all OLED screens called the AMOLED screen in Samsung. Since the OLED screen uses PWM dimming mode, it is easy to "hurt your eyes". Most of the LCD screen uses DC dimming mode, there is no such problem. 

    The OLED screen uses the PWM dimming mode, that is, the non-stop switching switch screen.  If the frequency of the switch reaches a certain extent, the naked eye is unable to distinguish. According to the IEEE document, the flash frequency reaches 3000 Hz to be harmless to the human eye. The flash frequency of Samsung, Apple, and other mobile phone OLED screens is only 250 Hz. The low-frequency flash will cause problems such as elevated intake, migraine, etc.; when the brightness of the screen is low, the frequency split rate will decrease, and it is easier to cause eye damage.

    Due to the innate advantages of the OLED screen, more and more manufacturers have been favored it. With the maturity of OLED technology, the cost is lowered. There will be more and more mobile screens in the future, which is unavoidable. The low-frequency flash of the OLED screen is one aspect of "injury". Others aspects such as the screen color is too bright, the blue light is not handled, the screen is too bright / too dark, etc. will cause certain damage to the eyes. When using the OLED screen, try not to use it in a dark environment and don't stare at the phone screen for a long time.

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