With the increasing resolution of LCD screen, the traditional interface can not meet the visual needs of people, so there are many new interfaces. In the aspect of LCD interface, the traditional LVDS has been more and more laborious in transmitting high-resolution signals, so the internal interface EDP (embedded DisplayPort) of DisplayPort appears. TTL (RGB), LVDS, EDP are commonly used interfaces for TFT-LCD. In this article, we will briefly talk about the signal composition and basic principles of these interfaces.
1. TTL Interface Overview
TTL (transistor transistor logic) is transistor transistor logic. TTL level signal is generated by TTL device. TTL device is one of the most important digital integrated circuits. It is made by bipolar technology and has the characteristics of high speed, low power consumption and many varieties. The TTL output interface of driver board generally includes RGB data signal, clock signal and control signal.
2. LVDS interface overview
LVDS, or low voltage differential signaling, is a low voltage differential signal technology interface. A digital video signal transmission method is developed to overcome the disadvantages of high power consumption and EMI in TTL level transmission of broadband high bit rate data. LVDS output interface uses very low voltage swing (about 350mV) to transmit data through differential on two PCB wires or a pair of balance cables, that is, low-voltage differential signal transmission. With LVDS output interface, the signal can be transmitted at a rate of several hundred Mbit / s on the differential PCB line or balance cable. Because of the low voltage and low current driving mode, low noise and low power consumption are realized. LVDS signal consists of data differential and clock differential signals.
3. In LCD TV, LVDS interface circuit is located between LCD scaler circuit and LCD panel. It consists of LVDS signal sending circuit (transmitter) on the main board side and receiving circuit (receiver) on the LCD panel side. LVDS transmitter converts the TTL level parallel RGB data signal and control signal output by scaler into low voltage serial LVDS signal, and then transmits the signal to LVDS receiver on LCD side through flexible cable (cable arrangement) between mainboard and LCD panel, LVDS receiver then converts the serial signal into parallel signal of TTL level and sends it to subsequent circuit (usually timing controller TCON)
Advantages of EDP interface:
(1) The micro packet structure can realize the simultaneous transmission of multiple data;
(2) Large transmission rate, up to 21.6 Gbps (4 pairs of lines);
(3) The smaller size, 26.3mn1 in width and 1.1mm in height, as shown in Figure 18, is very conducive to the lightness of the product.
In order to improve the data back transmission speed between panel and processor Zhidao, EDP interface has been widely used in computer and mobile terminal processor platform, and EDP interface is rapidly becoming the mainstream interface. Last year, Intel gave up the traditional LVDS interface in the new generation of Haswell processor platform and turned to EDP interface which supports embedded digital audio and video transmission.
Contact us
Name:Selina Chan
Tel:0086-596-2607595
Email:sales09@wiwotouch.com