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Structure and Composition of LCD Screens
Structure and Composition of LCD Screens
May 15th,2024
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I. Structure of the LCD Screen
TFT-LCD consists of the upper substrate assembly, lower substrate assembly, liquid crystal, drive circuit unit, backlight module, and other accessories. Specifically:
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The lower substrate assembly mainly includes the lower glass substrate and the TFT array.
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The upper substrate assembly comprises the upper glass substrate, polarizer, and a thin-film structure coated on the upper glass substrate.
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The liquid crystal is filled in the gap formed between the upper and lower substrates.
On the inner side of the lower glass substrate, there is an array of conductive microplates corresponding to the display pixels, TFT semiconductor switching devices, and connecting lines (both horizontal and vertical) linking these semiconductor switches. These components are formed through microelectronics manufacturing processes such as photolithography and etching. A cross-sectional view of the TFT semiconductor device for each pixel is as follows:
On the inner side of the upper glass substrate, a transparent conductive glass plate, typically made of indium tin oxide (ITO) material, is applied. This serves as a common electrode and forms a series of electric fields with the conductive microplates on the lower substrate. In the case of a color LCD, between the common conductive plate and the glass substrate, there are tri-color (red, green, blue) filter units and black dots. The black dots, made of opaque material, function to prevent light leakage from gaps between pixels. Arranged in a matrix pattern, they are referred to as the black matrix.
II. Components of the LCD Screen
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The LCD panel, commonly known as the glass, is the core component of the LCD module. The quality of a display largely depends on the LCD panel, which directly affects the visual experience. LCD panels are typically manufactured as large sheets and then cut into smaller sizes according to requirements, forming the core component.
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The LCD backlight refers to the light source behind the LCD module. Without a light source, the display would not show anything. The backlight consists of a light source, light guide plate, optical films, and other structural components. The brightness of the backlight can be controlled based on the LED chips and power consumption. If higher brightness is required, adjustments can be made to the backlight structure. However, brightness is not infinitely adjustable; it must be comprehensively designed considering the internal structure and overall power consumption.
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FPC (Flexible Printed Circuit) is a type of flexible circuit board characterized by high wiring density, lightweight, thinness, and good bendability. The LCD module uses FPC for electrical conduction to achieve display functionality. It is an indispensable component. While FPC is not the only means of electrical conduction—some larger screens may use interfaces like USB for power—FPC is commonly used for electrical conduction in small to medium-sized LCD modules.
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IC, commonly referred to as a chip, is a microelectronic device or component. Using specific processes, transistors, diodes, resistors, capacitors, inductors, and other elements, along with their interconnections, are integrated onto a small semiconductor wafer or dielectric substrate. The structure is then encapsulated within a housing to form a micro-structure with the required circuit functions. With ICs, various functionalities can be implemented.
