I. LCD TCON Control Board Principle
The TCON board, also known as the logic board or panel control board, is a key component of an LCD (Liquid Crystal Display) system. It mainly consists of five circuits: Power Management Circuit, Timing Control Circuit, Gate Driver Circuit, Source Driver Circuit, and P-Gamma Circuit. The TCON board has two main functions:
Signal Conversion: Converting the image signals (such as LVDS signals) output from the TV motherboard's Scaler into Mini-LVDS signals before outputting them. This conversion process ensures the signal is compatible with the LCD panel's driving requirements.
Signal Recognition and Driving: Converting the input LVDS image signals and clock signals into a list of working signals recognizable by the Panel Gate Driver and Source Driver. These signals include instructions to change the twist of liquid crystal molecules and scan the Gate, thus ensuring normal Panel driving.
II. Introduction to ICs in the TCON Board
The TCON board integrates various integrated circuits (ICs), each performing different functions and working together to achieve the core functions of the TCON board. Here are some key ICs and their functions:
Permanent Magnet IC: Responsible for generating various voltages required by the Source Driver, Gate Driver, Level Shift, and P-Gamma.
For example, after inputting 12V, this IC can output 5V, 3.3V, 1.8V, etc., to meet the needs of different circuits.
DVDD is the digital logic voltage, typically 3.3V, used to power the internal logic circuits of the IC; AVDD is the main voltage, primarily used for the pixel voltage output by the Source Driver and the voltage for Gamma correction; VGH is the Gate turn-on voltage, used to turn on the TFT gate; VGL is the Gate turn-off voltage, used to turn off the TFT gate; VCOM is the panel common electrode voltage, which varies depending on the panel.
Teekan IC: Responsible for converting the control signals, image signals, and clock signals at the Input end into signals that can be recognized by the Source Driver and Gate Driver.
Main pins include source signals such as CPV, STV, and CLK, and Gate signals such as STH, CPH, POL, and TP.
In this circuit, STV represents the image start input signal (Data Enable Pin), STH represents the Gate start signal (Gate Enable Pin), CLK is the Source data input clock, CPH is the Gate data input clock, POL is the LCD polarity flip start signal, and TP is the Source Driver lock data or output data indication signal.
Level Conversion IC: Its main function is to switch the input signal from one voltage domain to another.
Since the VDD values are different for different voltage domains, it cannot function properly without voltage conversion. Therefore, level conversion ICs use NMOS+PMOS or charge pump types to boost or drop the signal to meet the specifications of each voltage domain.
Gamma Integrated Circuit (Gamma IC): Performs Gamma encoding on the image, mainly to compensate for the characteristics of human vision through function calculations.
The purpose of Gamma encoding is to represent black and white data bits or bandwidth based on human perception of light or black and white. Since human vision's perception of light changes is not linear, Gamma ICs are needed to compensate for linear intensity differences in light to optimize human vision.
III. Development Trends of TCON Boards With continuous technological advancements, the IC portion of TCON boards is being gradually integrated to reduce the number of components, lower costs, and improve overall performance. In the future, we can closely monitor the subsequent development trends of components on the panel to understand the latest advancements in TCON boards and their ICs.
