一丶Composition of TFT-LCD panel
Disassemble the LCD panel, which can be divided into three main parts:
1. LCD panel
2. TFT panel
3. Backlight module
As for other driver ICs or iron frame structures used to fix these three parts, they will not be described separately; The specific decomposition diagram is as follows;
二丶The role of each part
1. Backlight source (or backlight module)
The backlight layer is actually the structure of the backlight source and the light guide plate, which is a light tube or light-emitting diode that can emit white light. The backlight source is mostly LED light source now. So when TV vendors refer to LED, they actually mean LCD with LED backlight, not real LED. Due to the fact that liquid crystal molecules themselves cannot emit light, in order to display images, liquid crystal displays require specialized light sources to provide light, which is then deflected by the liquid crystal molecules to produce different colors. The backlight serves to provide light energy. After the light tube (or LED) emits light, it is distributed to various places through a light guide plate, and the direction of all the light is concentrated towards the liquid crystal molecules through a reflective plate on the back. Finally, the light is evenly distributed through the prism sheet and diffuser plate to avoid situations where the central brightness is too high and the surrounding brightness is too low.
The above picture shows a light guide plate, which has a simple function of making the backlight uniform. Upon careful observation, it can be seen that the surface of the backlight panel is densely packed with dots that serve as light guides. Professional optical analysis and production are required to control the density of the dots at each position, thereby regulating the amount of light emitted by the light guide panel at that location. The precision designed light guide plate dots can evenly spread the incident light on both sides on the entire plane; If there are problems with the placement of the light tubes or the light guide plate in the backlight layer, it can easily lead to the appearance of a cathode ray screen;
There is also a layer of shiny reflective paper underneath the light guide plate, which has a simple function of reflecting the light from above back. Previously, mobile phones were relatively thick, and the entire backlight module was surrounded and protected by an iron frame. Nowadays, many projects omit the iron frame in order to make it thinner, which can lead to a problem. Once the bottom reflective paper is deformed by force, the reflected light is locally concentrated, resulting in water ripples on the surface of the screen;
2. Diffusion sheet
In the backlight structure, it mainly plays a role in correcting the diffusion angle, which increases the radiation area but reduces the light intensity per unit area, that is, lowers the brightness After being diffused by a diffusion material, the luminescent light source can become larger in area and have better uniformity;
3. Brightening film
Also known as prism film, it usually has two layers, mainly used to enhance brightness. The prism film is placed between the diffuser of the backlight and the liquid crystal panel. It can converge the light emitted from the diffuser uniformly at various angles to the axial angle, that is, the positive viewing angle, and improve the axial brightness without increasing the total emitted light flux; If the diffusion sheet or prism film is locally damaged, the exported light will have problems, resulting in white spots and other issues appearing on the screen;
4. Two polarizing films on the upper and lower layers
The function of polarizing film is to allow light to pass through in one direction. The polarizing layer is made by dyeing and stretching PVA film, which is the main part of polarizing film, also known as polarizing film. It determines the polarization performance and transmittance of the polarizer, while also affecting the color tone and optical durability of the polarizer.
5. Two glass substrates on the upper and lower layers
A glass substrate is not just two pieces of glass, it has a groove structure on the inside and is attached with an alignment film, which allows liquid crystal molecules to be arranged neatly along the grooves. TFT thin film transistors and color filters will be affixed on both sides of the upper and lower glass layers. The liquid crystal layer is sandwiched between two layers of glass;
6. Thin film transistor (also known as TFT)
We often refer to TFT-LCD, which actually refers to this thin film transistor. Its function is similar to a switch. TFT can control the signal voltage on the IC control circuit and deliver it to the liquid crystal molecules, determining the angle of liquid crystal molecule deflection. Therefore, it is a very important component.
7. Liquid crystal molecular layer
The liquid crystal molecular layer is the most important element that changes the polarization state of light, and its arrangement and polarization state are determined by both electric and elastic forces.
8. Color filter
The light deflected by liquid crystal molecules can only display different gray levels, but cannot provide the three primary colors of red, green, and blue (RGB). Color filters are composed of RGB filters, which are mixed to adjust the colors and brightness of each color. Each pixel in the LCD panel is composed of three dots: red, green, and blue, with each color dot having a different grayscale variation. A filter is made of plastic or glass with special dyes added. A red filter can only allow red light to pass through, and so on. The transmittance of glass sheets was originally similar to that of air, allowing all colored light to pass through, making them transparent. However, after dyeing, the molecular structure changes and the refractive index also changes, resulting in changes in the passage of certain colored light. For example, a beam of white light passing through a blue filter emits a beam of blue light, while green and red light are very rare and mostly absorbed by the filter
一丶Composition of TFT-LCD panel
Disassemble the LCD panel, which can be divided into three main parts:
1. LCD panel
2. TFT panel
3. Backlight module
As for other driver ICs or iron frame structures used to fix these three parts, they will not be described separately; The specific decomposition diagram is as follows;
二丶The role of each part
1. Backlight source (or backlight module)
The backlight layer is actually the structure of the backlight source and the light guide plate, which is a light tube or light-emitting diode that can emit white light. The backlight source is mostly LED light source now. So when TV vendors refer to LED, they actually mean LCD with LED backlight, not real LED. Due to the fact that liquid crystal molecules themselves cannot emit light, in order to display images, liquid crystal displays require specialized light sources to provide light, which is then deflected by the liquid crystal molecules to produce different colors. The backlight serves to provide light energy. After the light tube (or LED) emits light, it is distributed to various places through a light guide plate, and the direction of all the light is concentrated towards the liquid crystal molecules through a reflective plate on the back. Finally, the light is evenly distributed through the prism sheet and diffuser plate to avoid situations where the central brightness is too high and the surrounding brightness is too low.
The above picture shows a light guide plate, which has a simple function of making the backlight uniform. Upon careful observation, it can be seen that the surface of the backlight panel is densely packed with dots that serve as light guides. Professional optical analysis and production are required to control the density of the dots at each position, thereby regulating the amount of light emitted by the light guide panel at that location. The precision designed light guide plate dots can evenly spread the incident light on both sides on the entire plane; If there are problems with the placement of the light tubes or the light guide plate in the backlight layer, it can easily lead to the appearance of a cathode ray screen;
There is also a layer of shiny reflective paper underneath the light guide plate, which has a simple function of reflecting the light from above back. Previously, mobile phones were relatively thick, and the entire backlight module was surrounded and protected by an iron frame. Nowadays, many projects omit the iron frame in order to make it thinner, which can lead to a problem. Once the bottom reflective paper is deformed by force, the reflected light is locally concentrated, resulting in water ripples on the surface of the screen;
2. Diffusion sheet
In the backlight structure, it mainly plays a role in correcting the diffusion angle, which increases the radiation area but reduces the light intensity per unit area, that is, lowers the brightness After being diffused by a diffusion material, the luminescent light source can become larger in area and have better uniformity;
3. Brightening film
Also known as prism film, it usually has two layers, mainly used to enhance brightness. The prism film is placed between the diffuser of the backlight and the liquid crystal panel. It can converge the light emitted from the diffuser uniformly at various angles to the axial angle, that is, the positive viewing angle, and improve the axial brightness without increasing the total emitted light flux; If the diffusion sheet or prism film is locally damaged, the exported light will have problems, resulting in white spots and other issues appearing on the screen;
4. Two polarizing films on the upper and lower layers
The function of polarizing film is to allow light to pass through in one direction. The polarizing layer is made by dyeing and stretching PVA film, which is the main part of polarizing film, also known as polarizing film. It determines the polarization performance and transmittance of the polarizer, while also affecting the color tone and optical durability of the polarizer.
5. Two glass substrates on the upper and lower layers
A glass substrate is not just two pieces of glass, it has a groove structure on the inside and is attached with an alignment film, which allows liquid crystal molecules to be arranged neatly along the grooves. TFT thin film transistors and color filters will be affixed on both sides of the upper and lower glass layers. The liquid crystal layer is sandwiched between two layers of glass;
6. Thin film transistor (also known as TFT)
We often refer to TFT-LCD, which actually refers to this thin film transistor. Its function is similar to a switch. TFT can control the signal voltage on the IC control circuit and deliver it to the liquid crystal molecules, determining the angle of liquid crystal molecule deflection. Therefore, it is a very important component.
7. Liquid crystal molecular layer
The liquid crystal molecular layer is the most important element that changes the polarization state of light, and its arrangement and polarization state are determined by both electric and elastic forces.
8. Color filter
The light deflected by liquid crystal molecules can only display different gray levels, but cannot provide the three primary colors of red, green, and blue (RGB). Color filters are composed of RGB filters, which are mixed to adjust the colors and brightness of each color. Each pixel in the LCD panel is composed of three dots: red, green, and blue, with each color dot having a different grayscale variation. A filter is made of plastic or glass with special dyes added. A red filter can only allow red light to pass through, and so on. The transmittance of glass sheets was originally similar to that of air, allowing all colored light to pass through, making them transparent. However, after dyeing, the molecular structure changes and the refractive index also changes, resulting in changes in the passage of certain colored light. For example, a beam of white light passing through a blue filter emits a beam of blue light, while green and red light are very rare and mostly absorbed by the filter
