Past And Present Of Mobile Phone Screens: Can OLED Screens Become The Next Generation Of Display Technology?

- Sep 05, 2018-

   

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When you find something unusual, don't sneer at it. Maybe, you can change the world in front of you. In 1888, the 31-year-old F. Reinitzer was just a professor at Charles University in Prague. He was full of enthusiasm and enthusiasm. Perhaps it was to gain more respect in front of the students. He was in the experiment every day. The chamber studied its chemistry, and one day he synthesized a strange organic compound, Cholesterylbenzoate, and found that when the solid crystal was heated to 145 ° C, the solid in front melted into a turbidity. The liquid, while continuing to heat, turned into a clear liquid at 179 °C. He did not know at the time that the turbid liquid that had just appeared in front of him was the first human preparation for liquid crystal (Liquid Crystal). It was neither a gas nor a liquid or a solid, but a unique physical state. It is like a scorpion that is neither like a horse nor a horse, so the liquid crystal is called the scorpion of the organic world.


The portrait on the right is F. Reinitzer.

Although the existence of liquid crystals was discovered very early, it was not known how to use the photoelectric effect characteristics of liquid crystals. Until the 1960s, with the development of semiconductor integrated circuits, Americans successfully developed the first liquid crystal display (LiquidCrystalDisplay for short) and tried to apply it to digital quartz watches. However, they seem to be not fluent about this technology, so there is no mass production.


Sharp EL-805 calculator (picture from the network)

At this time, Japan, which was rebuilding the economic boom after the war, was more sensitive to the smell of new technologies. In a few years, several Japanese companies acquired the technology of LCD screens by purchasing patents. In 1972, the world's first calculator equipped with a TN-LCD as a display panel was born - the Sharp EL-805. Therefore, Sharp became the father of the LCD screen. But I believe that at the time, the Japanese should have dreamed that this black and white screen, which seems to only display a few numbers and applied to calculators and watches, will become the dominant technology for display technology in the future.

In order to let everyone know about the meaning of each screen evolution, I will give you a simple introduction to the working principle of the LCD screen. As we said before, the liquid crystal screen has photoelectric effect characteristics, specifically, the liquid crystal can interfere with the light passing through it, and by applying an electric field to the liquid crystal, it can control the interference of the liquid crystal to the light, and then cooperate with the polarizing plate to the light. The barrier property is achieved to control the intensity of light.


The most original reflective liquid crystal panel structure (1: polarizing plate 2: a specific area of the surface of the glass substrate is covered with a transparent electrode 3: liquid crystal layer 4: glass substrate 5 whose surface is covered with an electrode: polarizing plate 6: reflective layer)

The most original LCD screen is to place the liquid crystal material between two glass substrates, and then cover a specific area of the glass substrate with a transparent electrode, then add a polarizing plate on the outside of the substrate, and a reflective plate at the bottom. Screens of small electronic devices like electronic watches, calculators, etc., which are familiar to us, are almost always constructed like this. They can't shine on their own, so they can only rely on external light. When natural light hits the liquid crystal screen, the light passes through the first polarizing plate, allowing light waves of a specific direction to pass through, then passes through the glass substrate to the liquid crystal layer, and passes through the other polarizing plate to reach the bottom reflecting plate, and then the remaining The light is reflected back, but because the device is energized, the electrodes on the glass substrate receive a voltage signal that affects the liquid crystal in a particular area, causing them to change the path of the light, resulting in that the part is affected by the electric field. The liquid crystal area cannot pass through the light, so that it is displayed in black on the screen to achieve the purpose of displaying information.


Martin Cooper and the world’s first truly mobile phone

On April 3, 1973, an engineer named Martin Cooper, who was on the streets of New York, put a white brick on his ear, still talking to himself. This turned out to be the first mobile phone of human beings. It is huge, weighs 2 pounds, charges 10 hours, calls for 20 minutes (...) There are also many digital buttons on the surface, but there is a regret that it is impossible to display the number when dialing, it is very easy to press the wrong Not aware of it. So in the follow-up products, the LCD screen for displaying the number appears.