Classification by material of LCD
Currently, the mainstream screens of smartphones can be divided into two categories:
- LCD(Liquid Crystal Display) is a liquid crystal display screen that needs to be illuminated by a backlight to display. It can be divided into TFT, incell, etc. The current LCD screens are all hard.
- OLED(Organic Light-Emitting Diode) is an organic light-emitting diode. OLED screens are self-luminous and are divided into two types: hard OLED screens and soft OLED flexible screens. The substrate and encapsulation layer of the hard screen are both glass and cannot be bent; the substrate of the flexible screen is flexible PI, and the encapsulation layer is thin film, so it is flexible. Folding screens, curved screens, and Xiaomi’s surround screens on the market are all flexible OLED displays.
Comparison of LCD and OLED displays
| Performance | OLED | LCD |
| Luminous Mechanism | Self-illuminating, no backlight required | Self-illuminating, no backlight required |
| Display Brightness | High brightness, can be displayed under sunlight | Low brightness and difficult to use in sunlight |
| Reaction Speed | Very fast, in microseconds, 100 times faster than LCD | Very low, measured in milliseconds, causing ’’smearing’’ |
| Display Distortion | Very little | Obviously, with horizontal and vertical viewing angle distortion |
| Perspective | All directions can exceed 160° | Limitation, especially vertically |
| Thickness | Can be less than 2mm | At least 1cm or more |
| Softness | Flexible display panels can be made from plastic substrates | Cannot be made into a bendable display panel |
| Power consumption | Extremely power-saving, a 40-inch color TV consumes 80-100 watts | A 40-inch color TV with CCFL backlight consumes 290 watts |
| Lifetime | Low, currently about 5000 hours | Long lifetime, 10000-15000 hours |
Classification according to the quality of LCD screens
Currently, the quality of smartphone screens can be divided into two categories: original and assembled.
Original screen: refers to the screen produced by the original mobile phone manufacturer. The advantage is that each performance is most suitable for mobile phones; the only disadvantage is that it is expensive. The original screen is subdivided into:
- Original new screen
- Original used/disassembled
- Original changed glass
- Original self-welded(using raw materials, or the original screen with a broken external screen, separated from the external screen, and then assembled)
Assembled screen: processed by a small factory, the advantage is low price; disadvantage: touch insensitivity and image display smear may occur.
According to different processing and production technologies, it can subdivided into:
- The difference between on-cell and previous screens is that the touch sensor is made on the CF panel of the LCD, instead of the traditional technology combination of touch+LCD.
- The in-cell touch sensor is designed into the LCD(array layer) liquid crystal. In comparison, incell has a higher technical content. The advantage of this technology is that it can make the screen thinner.
- COG(Chip on Glass) chip is directly bound to the glass. This installation method can greatly reduce the size of the LCD module and is easy to mass produce. The advantages of the COG process: are low power consumption; smaller size; good shock resistance; and cheap price.
- TFT(Thin Film Transistor) is a thin film transistor display that has the advantages of high responsiveness, high brightness, and high contrast, but it consumes more power.
- OLED(Organic Light-Emitting Diode) is organic light-emitting diode. It refers to the phenomenon that organic semiconductor materials and luminescent materials cause luminescence through carrier injection and compliance when driven by an electric field.
- OLEDⅡ/OLED 2 is similar to the TFT process, except that the backlight is made of iron and is thinner than TFT.