What is an LCD screen with a MIPI interface?
MIPI interface LCD screen refers to a LCD screen that uses the D-PHY physical layer and DSI protocol standards developed by the MIPI Alliance to communicate with processors on the motherboard (such as mobile SoC, tablet CPU).
This is a very comprehensive explanation of "LCD screens with MIPI interfaces.".
I. Core Definition: A one-sentence explanation of what it is
The MIPI interface LCD refers to a liquid crystal display that communicates with the processor on the motherboard (such as smartphone SoC or tablet CPU) using the D-PHY physical layer and DSI protocol standards established by the MIPI Alliance.
Simply put, it is a high-speed, low-power, anti-interference "video transmission solution" specifically designed for internal displays in mobile devices (such as smartphones, tablets, drones, AR/VR devices, etc.).
II. Detailed Breakdown: Key Components of the MIPI Interface
LCD screens with MIPI interfaces typically refer to those adopting the MIPI DSI standard, where DSI is the dedicated component for display purposes.
MIPI DSI
Full name: Display Serial Interface
Function: It serves as a serial bus interface between the motherboard processor and the display module. The processor packages and transmits image data to the screen via the DSI bus.
MIPI D-PHY
Function: This is the electrical standard implemented by the DSI protocol at the physical layer. It specifies signal voltage, timing, cable characteristics, and more.
Key Features:
Differential signal: Utilizes differential data pairs (e.g., Data0+ and Data0-) for data transmission, offering exceptional resistance to electromagnetic interference, making it ideal for long-distance, high-speed transmission in complex electromagnetic environments within devices.
High-speed/Low-power mode:
High-speed mode: Used for transmitting large amounts of image data at very high speeds (up to several Gbps).
Low-power mode: When screen updates are not required (e.g., displaying static content), the device enters a state of extremely low power consumption, functioning solely for command transmission, thereby significantly conserving battery power.
III. Main features and advantages
Compared with traditional parallel RGB interfaces and LVDS interfaces, MIPI DSI interface LCD screens have the following outstanding advantages:
High speed: Using serial differential signals, the data transmission rate is extremely high, which can easily support high-resolution (such as 2K, 4K) and high refresh rate (such as 90Hz, 120Hz) screens.
Low power consumption: It has an independent low-power mode, which is a feature tailored for battery powered mobile devices and can significantly improve the device's battery life.
Strong anti-interference ability: The differential signal structure gives it natural immunity to common mode noise, good signal integrity, and stable image quality.
Few pins and simple wiring:
Traditional parallel RGB interfaces may require over 20 data cables.
MIPI DSI typically only requires 1 pair of clock lines and 1 to 4 pairs of data lines (such as 1-lane, 2-lane, 4-lane). This simplifies the connector design and internal wiring between the motherboard and screen, saving space and reducing costs.
Compact packaging: Due to the small number of wires, the connector can be made very small, which is very suitable for mobile devices that pursue slimness.
IV. Physical interfaces and connections
On a typical MIPI DSI interface screen's FPC (flexible circuit board), you will see paired differential lines:
CLK+/CLK -: Differential clock line pair.
DATA0+/DATA0-: The first pair of differential data lines.
DATA1+/DATA1-: Second pair of differential data lines.
... (There may also be DATA2, DATA3)
VCC: Positive pole of power supply.
GND: Power Ground.
Reset, backlight control, and other control signals.
The number of data channels determines the bandwidth of data transmission. A screen with higher resolution and refresh rate requires more data channels (for example, 4 lanes>2 lanes>1 lane).
V. Application Fields
The MIPI DSI interface LCD screen is almost a standard configuration for the following devices:
smartphone
tablet
Portable gaming consoles (such as Nintendo Switch)
Image transmission display screen of drone
AR/VR headset devices
Smart Watch/Bracelet
in-vehicle display
Various embedded devices and industrial control devices
VI. Key points to note
Non direct drive: MIPI DSI is a "command based" interface that does not directly output row field synchronization signals and RGB data points like traditional RGB interfaces. The processor sends data packets, and the receiving chip on the screen (usually integrated with the driver IC) unpacks these data and converts them into the signals required to drive the LCD panel.
Initialization sequence: After the MIPI screen is powered on, the main processor needs to send a series of specific initialization commands through the DSI bus to configure the screen's driver IC before the screen can start working normally. These command sequences are usually provided by screen manufacturers.
Compatibility issue: Although MIPI is a standard, the initialization sequence and timing parameters of screens from different manufacturers and models may be completely different. Therefore, in hardware design, the motherboard must write corresponding driver programs for specific MIPI screen models.
Summary
The MIPI interface LCD screen is a display solution optimized for mobile and embedded devices. With its high speed, low power consumption, strong anti-interference, and simple wiring, it has become the absolute mainstream technology for mobile smart device displays today. When you open a smartphone, the slender ribbon cable connecting the motherboard and screen transmits MIPI DSI signals.
