A common feature in modern keyboard advertising is the keyboard being “mechanical”. Unfortunately, exactly what this means and what the alternatives are, is generally not very well explained.
What is a mechanical keyboard?
A mechanical keyboard uses a mechanical switch to signal if the key has been pressed or not. The switch is comprised of three parts, a keycap, stem, and switch. The keycap is the actual key that is pressed, it is typically removable (with care). The stem is the active part of the key, that is pushed down when the keycap is pressed, it is pushed back up by a spring.
An arm on the stem is used to open and close the switch. By changing the shape of the arm, the tactile experience of the keypress can be changed. There are plenty of different tactile options available. The most common brand of switches is “Cherry MX”, each variant of its switches uses a different colour plastic with the colour being used as the name of the switch. For example, the Cherry MX Brown switch has a slight bump on the arm of the stem, which causes a small but noticeable change in resistance to depressing the key. As soon as the increased resistance is passed the switch closes and the keypress registers.
What are the alternatives?
There are two main alternatives to mechanical keyboards: membrane and scissor-switch. A membrane keyboard uses a thin sheet of rubber or silicone that has small domes for each key with a small conductive strip on the underside. When a key is pressed, the dome is pushed down, and the circuit is completed, registering the activation of the key. When the key is released the rubber/silicone dome returns to its original shape.
A scissor-switch keyboard still uses a rubber/silicone dome, but the keycap is attached to the keyboard with a set of interlocking arms in a “scissor” like fashion. This style of keyboard typically has a very low profile and is often used on laptops
Advantages and disadvantages
One of the key selling points of the mechanical keyboard is its superior tactile experience. Various stem shapes are available with variations on the experience, most of them offer some level of extra resistance as the key activates. Membrane keys generally don’t offer much in the way of tactile feedback beyond bottoming out the key. With usage over time, the resistance offered by the membrane dome can decrease making using it feel mushy.
With mechanical keyboards, key activation occurs partway through the keypress, in comparison membrane style keyboards need to be pressed all the way to the bottom for the circuit to complete. This marginally decreases the time required for the key to be detected as pressed. It also allows users to use less force on the keys when typing and avoiding bottoming the keys out entirely.
Mechanical keyboards sound a lot louder, generally somewhat like an old typewriter. For some people, this is a good thing, but a lot of people don’t like how loud the keyboards sound, with even the quieter switches being loud. In many scenarios such as in gaming and on Skype calls, the sound of typing can be picked up by a microphone. Membrane keyboards are significantly quieter, with most of the sound being from keypresses bottoming out as a dull thud. Scissor switch keys tend to be a little louder than that with a higher-pitched clicking sound.
The spring underneath a mechanical key can be configured as well allowing for extremely light or unusually heavy keypresses as preferred by the user.
Mechanical key switches are designed for a significantly longer lifespan than membrane keyboards. Cherry MX switches are rated between 20 and 50 million keystrokes depending on the type of switch. In comparison, membrane keyboards are generally rated for 5 million keystrokes.
The added complexity of construction, along with the marketing of mechanical keyboards being a premium option; means that mechanical keyboards are generally more expensive than membrane keyboards.
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