Considering LCD Connector Options
Understanding the different types of display connections can aid you in selecting which is best for you and which components to use. Different boards have different display capabilities. When deciding which system and which choices are best for you, bear in mind what you might want to accomplish with your system in the future, not just now. A few major types of connectors are found across the industry, such as FPC/FFC connectors, through holes, metal pins, heat seals, and ZEBRA strips.
Firstly, it is important to consider connectors because they are what will transform commands and, ultimately, communication to the LCD by connecting to the screen and the LCD driver. The LCD driver is an integral component of most LCDs. It has a CPU, memory (RAM and ROM), video, audio, and other interfaces (input/output ports). Unlike a microprocessor or microcontroller, built for a wider range of applications, an LCD driver is dedicated to one task: controlling the LCD. The LCD's driver is the display's brain. Its main job is to convert firmware into letters, numbers, and graphics for the LCD.
FFC or Flexible flat cables (also known as flat ribbon cables) are a form of ribbon cable with a broad flat construction. Flexible printed circuits are also widely used in the industry (FPC) and can be considered interchangeably. They are generally only a straight connection with no other parts. FFC cables typically consist of a plastic sheet to which many metallic connectors are connected. FFC cables are smaller and more flexible than round cables, and they frequently provide superior EMI/RFI suppression and eliminate wire coupling difficulties. They are commonly employed in high-density electronic systems, particularly when great flexibility is required, such as connections to a moving printer head, folding mobile phones, or where weight or space constraints exist. While FPCs are bendable, it should be noted to avoid fully compressing the cable to prevent damage to its internal circuitry. The minimum bend radius may vary depending on the FPC, but typically the rule is to avoid any creasing of the cable.
Many displays allow a connection through tiny holes on the PCB called through holes. LCDs with an external PCB controller circuit affixed to the display, such as most character LCDs, use this connection type frequently. A liquid crystal driver, a voltage conversion circuit, and backlight control are usually included on the PCB. Through holes are PCB holes with conductive metal that may be linked using solder or a bezel. The display may be connected and interfaced in a variety of ways with a through-hole connection. Because of the consistent pitch between holes and the broad range of possibilities for connection, attaching the display through through-holes is an excellent option for prototyping or testing. The major limitation with through-holes is the amount of space these tend to take up; they have standard sizing, making them easy to plug into a breadboard or other peripheral devices.
Heat seal connections for LCDs are a secure connection method that uses a flexible cable connector that is heated and sealed to the interface ports of the display. This connection is made with a special heat seal paper, which is applied to the display with conductive adhesive and then sealed with heat. Heat seal connections are used in hinged situations where the display is situated at a different angle than the port. It is worth noting that heat seal connections have become much less common over the past 20 years and it is more common for new designs to use an FPC or FFC ribbon cable instead.
Metal pins are a sort of connection that is used with LCDs that already have metal pins attached and linked to the display. Metal pins can be linked to an LCD's COM and Segment lines or the internal display controller. Character and segment LCDs often employ this connection type. Metal pins are great for applications with conventional pin mappings, which allow the display to be connected to the controlling device. Because the pins are hardwired into place and cannot be relocated unless unsoldered, this connection type is less adaptable than other LCD connection types.
Elastomeric or ZEBRA connectors are electrical connectors with a unique design that includes numerous alternating layers of conducting and insulating materials. These layers are frequently grouped in a striped pattern. The first layer might be made of conductive material, followed by an insulating layer and another layer of conductive material. Despite its simplicity, this design has proven to be quite beneficial in creating electrical connections. Even though elastomeric connections come in various shapes and sizes, they always have the same fundamental design: a horizontal polymer bar with alternating layers of conducting and insulating material. The connector is subsequently fitted between the device's contact regions, which assists in controlling the power flow. Because there is no need to connect pins to the display permanently, this connection type is a popular choice for testing and prototyping displays. ZEBRA strips are also a fantastic choice for LCD and PCB designs that are small and compact. A ZEBRA strip, for example, can be used instead of metal pins or ZIF connections if space is restricted within the enclosure. ZEBRA connectors are also frequently a less expensive option than other forms of connections.
While there are many different types of connectors to consider, the key variables to consider are cost, prototyping, and the connection's permanence. Focus LCDs offers a broad range of LCD panels, with various connectors and drivers that can be by your side in nearly any LCD project, end-to-end.