What is a key cartridge? What is the difference between a key cartridge and a keyboard?

Everyone knows what a keyboard is, but many people don't know what a key core is. A key core is the core mechanical component that triggers key presses (commonly found in mechanical keyboard switches). It's not the same concept as a keyboard; they are related as a partial component and a complete input device, with clear distinctions. The following explains its definition, relationship, and core differences:

I. What is a Key Core?

① Definition: A key core (stem) is the core sliding component within a mechanical keyboard switch. Working with springs and contact/optical components, it's responsible for transmitting the pressing action, triggering the electrical signal, and determining the key's feel, travel distance, and actuation feedback.

② Structure and Function: Located between the switch's top cover and base, it closes the contacts/changes capacitance/blocks the optical path when pressed, and returns to its original position via a spring when released. The material (e.g., POM, nylon, PC) and shape directly affect smoothness, sound, and stability.

③ Scenarios: Commonly found in mechanical switches, optical switches, and capacitive switches. Membrane keyboards do not have independent key cores; they rely on a membrane circuit layer for actuation.

II. Core Differences Between Keyboards and Keyboard Cores

1. Different Fundamental Roles: Keyboard: A complete computer input device; Keyboard Core: The core mechanical component that triggers key presses.

2. Different Core Components: Keyboard: Shell, keycaps, switches (including keyboard core), PCB, mounting plate, MCU, etc.; Keyboard Core: Switch body, spring, contact/optical elements (core component within the switch).

3. Different Functional Scope: Keyboard: Receives keystrokes, scans codes, transmits signals, and provides a human-computer interaction interface; Keyboard Core: Only responsible for converting physical pressure into electrical signals, providing tactile feedback.

4. Different Replaceability: Keyboard: A complete device; some mechanical keyboards allow for switch replacement; Keyboard Core: The keyboard core can be replaced individually within a mechanical switch (common in custom keyboards).

5. Typical Lifespan: Keyboard: Depends entirely on the structure and switches; mechanical keyboards typically have a lifespan of 50 million keystrokes; Keyboard Core: Lifespan is the same as the switch; high-quality keyboard cores can reach tens of millions of keystrokes.

III. The Relationship Between the Two

1. The key stem is the core of the switch, and the switch is the core of a mechanical keyboard; membrane keyboards do not have independent key stems, relying on membrane circuitry for actuation.

2. The key stem determines the feel of a single key (linear/tactile/click), while the overall keyboard experience is also affected by keycaps, mounting plate, PCB, and casing.

3. Replacing the key stem can fine-tune the switch feel (e.g., replacing with a POM key stem to improve smoothness), but it requires compatibility with the switch specifications and is considered an advanced customization operation.

Therefore, the key stem is the core actuation component of a mechanical keyboard switch, and the keyboard is a complete input device that includes the key stem.