What Is a LCD Module?
An LCD Module is an LCD panel, which constitutes of an LCD display, and a driver/controller for displaying images.
Because they are relatively inexpensive, thin, and have low power consumption, they are incorporated into a wide variety of electronic devices. In addition to embedded devices, they are often used as components for electronic crafts.
There are two main types of LCD modules: character LCD modules, which specialize in displaying text, and graphic LCD modules, which can also display graphics and illustrations.
Uses of LCD Modules
The range of applications for LCD Modules is expanding day by day, and there are no limits to the number of uses for LCD Modules.
1. Portable Devices
In portable devices such as smartphones, tablets, and laptops, LCD Modules are a central component of the user interface. They receive the user’s touch input and display information clearly, greatly enhancing the usability of these devices.
2. Home Appliances
LCD Modules are used in home appliances such as televisions, refrigerators, air conditioners, and washing machines to display information and provide operational guidance. For example, in televisions they are used to display images, and in refrigerators and air conditioners they are used to display temperature and setting modes.
3. Industrial Equipment
LCD Modules are also used in the operation panels of industrial equipment such as factory production lines, agricultural machinery, and construction equipment. They provide the operator with necessary information to enable safer and more efficient equipment operation.
4. Medical Equipment
LCD Modules also play an important role in the medical field. They are installed in devices that monitor vital signs of patients, ultrasound machines, MRI scanners, etc., and provide necessary information visually to medical personnel.
5. Automobiles
In modern automobiles, LCD Modules are used to display information such as vehicle speed, engine status, and navigation information.
Principle of LCD Modules
To understand how Liquid Crystal Display (LCD) Modules work, one must first understand the properties of liquid crystals. Liquid crystals are substances in a state between that of a solid and a liquid, and can be oriented by temperature or an electric field. This property is the core principle behind LCDs.
1. Liquid Crystal
Some liquid crystals have the ability to change the polarization of light, and LCDs use this ability to produce images. Specifically, applying voltage to a liquid crystal cell (consisting of a liquid crystal layer and electrodes on both sides) changes the orientation of the liquid crystal, resulting in a change in light transmittance.
2. LCD Module
The LCD Module consists of the display part based on the liquid crystal cell and the electronic circuits that control it. The electronic circuit applies a voltage to each liquid crystal cell in response to an input signal and controls the light transmittance of each cell. This creates a complex image when viewed as a whole display.
3. Color Display
For color display, this is usually achieved by combining backlight and color filters for the three primary colors of red, green, and blue. Each pixel consists of three liquid crystal cells (corresponding to red, green, and blue respectively), and the transmittance of each cell can be controlled to produce any desired color.
Types of LCD Modules
LCD Modules are broadly classified into three types according to their construction and assembly methods. They are called COB type, COG type, and COF type, respectively, and have different characteristics and application fields.
Each of the three types is selected based on factors such as product characteristics, field of application, and manufacturing cost.
1. COB Type (Chip-On-Board)
The COB type refers to a type in which the LCD panel and IC chip are mounted on the same printed circuit board. All functions can be mounted in a single unit, but this type has the disadvantage that it tends to be large in size.
2. COG Type (Chip-On-Glass)
The COG type refers to a type in which the IC chip is directly mounted on a glass substrate (LCD panel). This enables thinner and smaller modules. However, passive components are externally mounted.
3. COF Type (Chip-On-Film)
COF type refers to a type in which IC chips are mounted on a flexible film substrate. COF type, like COG type, can be made thinner and smaller, and can also be applied to curved surfaces.
Other Information on LCD Modules
1. LCD Structure Details
Major components of liquid crystal displays (LCDs) include polarizing filters, glass substrates, transparent electrodes, alignment films, and color filters.
- Polarizing Filters
Located on the outermost layer of the LCD is the polarization filter. This filter is responsible for allowing only light in a specific direction to pass through. Two polarizing filters are used in an LCD cell, with a liquid crystal layer sandwiched between them. - Glass Substrate
There are two transparent glass substrates used to make up the liquid crystal cell. The liquid crystal is sealed between these substrates. - Transparent Electrode
A transparent electrode is deposited on one side of the glass substrate. This serves to apply voltage to the liquid crystal layer. - Alignment Film
An alignment film is applied on top of the transparent electrode. This film is used to align (orient) the liquid crystal in a certain direction. - Color Filter
In a color LCD, a color filter is placed on one side of the glass substrate. These filters correspond to the three primary colors: red, green, and blue, and they determine the color of each pixel.
2. Display Method of LCD Module
There are three display methods for LCD Modules:
- Segment Method
This method displays numbers by arranging elongated display units in a numerical figure-eight pattern. - Dot Matrix Type (Character Display)
A method in which display units are arranged in a vertical and horizontal matrix to form characters. - Dot Matrix Principle (Graphic Display)
A method that arranges display units in a vertical and horizontal matrix to draw figures and other objects.
In color display, RGB color filters are applied to each display unit, and various colors are expressed by combining them.