According to the above LCD display of the anatomy, it can be seen that the composition of the liquid crystal display is not complex, LCD panel and the corresponding drive plate (also called the motherboard, pay attention to is not in the LCD panel in the ranks of the drive circuit), power panel, inverter, key control panel, etc., make up a complete LCD display.
Below is a brief description and liquid crystal display each component of the function and the position of the actual circuit.
1. The power section
Liquid crystal display of power supply circuit is divided into switching power supplies and DC/DC converter two parts. Among them, the switching power supply is a kind of AC/DC converter, its function is to mains AC 220 v or 110 v (European standard) into 12 v DC power supply (some models for 14 v, and v and 24 v or and v), supply DC/DC converter and inverter circuit; DC/DC DC converter with switching power supply to produce DC voltage (such as 12 V) into 5 V, 3.3 V, 2.5 V, such as voltage, supply drive plate and the LCD panel and use.
At present, the liquid crystal display of switch power supply, there are two major kinds of installation forms: (1) the external power Adapter (Adapter), so, input display voltage is power Adapter device output dc voltage; (2) in the display internal AD hoc a switch power panel, the so-called inscribed way, in this way, on display input is ac 220 v voltage.
DC/DC converter to also have a variety of installation, the first kind is AD hoc a DC/DC conversion board; The second is and switch power supply part installed together (switch power supply is built-in type); The third kind is installed on the main board.
2. The driver board (motherboard) part
Drive plate is also called the mainboard, is the core of the liquid crystal display circuit, which mainly consists of the following components:
(1) the input interface circuit
Liquid crystal display general equipped with transmission of the analog signal VGA interface (D - Sub interface) and transmission of digital signal DVI interface. Among them, the VGA interface used to receive a host graphics output die quasi R, G, B and line field synchronous signal. DVI interface for receiving host graphics TMDS (minimize transmission differential signal) transmitter output TMDS data and the clock signal, receives the TMDS signal need to pass LCD monitor internal TMDS receiver decoding, can add to Sealer circuit, however, now many TMDS receiver are integrated in the Scaler chip.
(2) A/D conversion circuit
A/D conversion circuit is analog-to-digital converter to will VGA interface output analog R, G, B signal is converted to A digital signal, and then to the Sealer circuit for processing.
Early LCD display, generally A separate A piece of A/D conversion chip (such as AD9883, AD9884, etc.), now the production of liquid crystal display, mostly have A/D conversion circuit set into the Scaler chip.
(3) clock generator (PLL phase lock loop circuit)
Clock produce circuit receiving line synchronization, field synchronous and external crystal oscillator clock signal, the clock generator produces the clock signal, on the one hand, to the A/D conversion circuit, as the sampling clock letter number; On the other hand to Sealer circuit for processing, produce drive LCD screen pixel clock.
In addition, liquid crystal display modules internal coordination work also need the clock signal with to complete. Display clock generator generally all by phase locked loop (PLL) circuit to control, in order to improve the stability of the clock.
Early LCD display, the clock generator integrated in ? A/D conversion circuit, now the production of liquid crystal display, mostly in the clock generator integrated chip Sealer.
(4) Sealer circuit
The name of the Sealer circuit more, like scale circuit, control circuit, image controller, etc. The core of the Sealer circuit is A large scale integrated circuit, called Sealer chip, its function is to get A/D conversion of digital signal or TMDS receiver output data and clock signal, scale, quality enhancement processing, then the output interface circuit sent to the LCD panel, finally, the liquid crystal panel of the sequential control IC (TC0N) will signal transmission to the panel line driver IC. The performance of the chip Sealer basically determines the limit of the signal processing ability. In addition, in the Sealer electric road, the general has integrated a screen show circuit (0 sd circuit).
Liquid crystal display why to signal scale processing? This is due to a panel painting prime position and resolution in the manufacturing is done, have fixed, but video device output resolution is diverse, when LCD panel must receive different resolution video signal, then after scaling processing can be suitable for a screen size, so signal need to pass Sealer chips for scale processing.
(5) micro controller circuit
Micro controller circuit mainly includes MCU (micro controller), memory, etc., among them, the MCU is used to display key information (such as brightness adjustment, position adjustment, etc.) and display itself state control system information (such as no input signal recognition, power on self, all kinds of provincial electric energy saving mode conversion, etc.) to control and processing, to complete the specified function operation. Memory (here refers to the serial EEPROM save memory) used to store liquid crystal display device in the operation of the data and the data, including the set of basic parameters, manufacturers, product type, resolution data, maximum line frequency, field refresh rate, including the set of running status of some data, such as white balance data, brightness, contrast, all kinds of geometric distortion parameters, the state of the energy saving control data, etc.
At present, a lot of liquid crystal display will be the memory and MCU integrated together, and some liquid crystal display and even the MCU, memory are integrated in the Scaler chip. Therefore, in the liquid crystal display device driver board, is can't see the memory and the MCU.
(6) output interface circuit
Drive plate and LCD panel interface circuit has a variety of, commonly used mainly has the following five kinds:
The first is a parallel bus TTL interface, used to drive TTL LCD screen. According to the different panel resolution, and l interface is divided again and bit or 24 bit parallel digital signal.
The second interface is now very popular low pressure difference LVDS interface, used to drive LVDS LCD screen. Compared with 17 l interface, serial interface has a higher rate, lower electromagnetic radiation and electromagnetic interference, and need the data transmission line is better than parallel interface a lot less, so, from the point of view of technology and cost, LVDS interface than 1 tl good. Those who need a specification is, those who have LVDS interface LCD display, on the mainboard general need a LVDS send chip (some may be integrated in the Sealer chip), at the same time, in the LCD panel should have a piece of LVDS receiver.
The third is the RSDS (low amplitude signal) interface, used to drive RSDS LCD screen, the RSDS interface, which can significantly reduce the radiation intensity, production crystal more healthy environmental protection, and can enhance EMI anti-interference can force, make the picture quality clearer stability.
3. According to the keypad part
Key circuit installed in key control panel, in addition, light are also commonly installed in button on the control board.
Key circuit role is to make the circuit on and off, when press the switch, key electronic switch on; Hand loosen, key electronic switch off. Key switch output switch signal to the driver board in the MCU, the MCU recognition, the output control signal to control the related circuit complete corresponding operation and action.
4. Inverter part
High voltage inverter commonly known as a (for circuit board is generally long, for strip form), sometimes referred to as inverter circuit or inverter, its function is to power output of the low voltage dc voltage into liquid crystal board (Panel) the high frequency high voltage alternating current (ac) more than 600 v, lit LCD Panel backlight.
There are two main types of dv6-1150el Inverter installation forms: (1) AD hoc a circuit board; (2) and switch power supply circuit mounted (switch power supply is built-in type).
5. LCD Panel (Panel) part
LCD liquid crystal display panel is the core components, mainly include LCD screen, LVDS receiver (optional LVDS LCD screen, the circuit), driver IC circuit (including source driver IC and grid driver IC), sequential control IC (TC0N) and the back light.
Finally, the need to emphasize, liquid crystal display circuit structure and color TV, CRT display sc-reens, developed from more pieces of integrated circuit ? monolithic integrated circuit ? super single chip development process. For instance, early LCD display, A/D conversion, clock generator, Sealer and MCU circuit adopts independent integrated circuit; Now the production of liquid crystal display, then most of the A/D conversion, TMDS receiver, clock generator, Sealer, 0 sd, LVDS transmitter integrated together, some even will MCU circuit, TC0N RSDS, such as integrated circuit is in, be A real "super chip". No matter use which kinds of liquid crystal display circuit form, but all things become not depart from the Pope, that all LCD display basic structure is the same or similar, as maintenance personnel, as long as the understanding of the liquid crystal display basic structure and composition, and then combined with the main factory to provide integrated circuit pin function, it is not difficult to identify the overall circuit of the basic work process.
|
