Segmented LCDs, also called "segment displays", are the most basic type of liquid crystal display. You probably see them every day. Common examples include numbers on calculators, digital multimeters, and early digital watches.

To understand this, let’s look at it in a few ways:

1. Core Principle: Pre-defined "Segments"

As the name suggests, the content displayed on a segmented LCD is composed of a series of pre-fabricated graphic segments.

An Analogy: Think of the number cards we played with as children. A card might have a printed "8" on it; when you needed to represent the number "3," you would mentally focus only on the specific segments that make up the shape of a "3." The difference is that, on a screen, this process is controlled by electrical signals.

Common formats: The most common type of segment display is the "7-segment display", which is used to show numbers. The display has eight shapes, and each one has seven parts. These parts can be lit up in different ways to make any digit from 0 to 9.

Customization: Extra symbols like battery, Bluetooth, or thermometer icons can be added. Once manufactured, the physical positions of these specific display areas are permanently fixed.

2. Key Characteristics: Not Designed for Playing Movies

Segmented LCDs are different from smartphone displays in a few ways:

Fixed content: Can only show pre-designed numbers, letters, or icons—no images or flexible text.

Low cost: Simple design makes them very cheap to produce.

Low power use: Rely on ambient light, so they consume very little energy and can run for years on small batteries.

Needs lighting: Not self-illuminating; requires ambient light or a backlight to be visible.  

3. Application Scenarios: Industrial Equipment and Consumer Goods

Segmented displays are still used in many areas because they are cheap, energy efficient and easy to see in sunlight.

Instrumentation: Multimeters, utility meters, glucose and blood pressure monitors.

Home appliances: Older microwaves, AC remotes, calculators.

Automotive: Old-style dashboards.

A Brief Summary

Segmented LCDs (segmented displays) are a type of "old-school" screen. They are specially made to show fixed numbers and symbols. It is energy-efficient and low-cost. It's limited to simple numbers and icons, but it's perfect for basic displays.