How do Computer Keyboards Work? 🤔⌨⌨🛠

Summary

This video script explores the engineering marvels behind basic computer keyboards, focusing on cost reduction. It dissects an inexpensive keyboard with only 8 critical parts, costing as low as $1.57 each, and explains how it functions using a simple matrix system. The script contrasts this with a high-end mechanical keyboard, costing over 50 times more, revealing the intricate mechanisms behind its tactile feedback and clicking sound. The video also touches on laptop keyboards and emphasizes the importance of engineering education.

Takeaways

• 😲 Basic computer keyboards have surprisingly impressive engineering, particularly in cost reduction.
• 💰 The inexpensive keyboard is made up of only 8 critical parts, allowing for bulk purchases as low as $1.57 each.
• 🔍 Inside the cheap keyboard: a rubber sheet with domes, three plastic sheets with conductive wires, and a simple circuit board with components.
• ⚙️ The keyboard's functionality relies on a matrix system where keys press domes to bridge conductive traces on plastic sheets.
• 🔋 The keyboard matrix uses a method of scanning columns with 3 volts and detecting row inputs to identify key presses.
• 🔌 The microprocessor sends key data to a 2.4 GHz transceiver, utilizing printed planar antennas for wireless communication.
• 💡 Mechanical keyboards, costing over 50 times more, have a different internal mechanism, including a spring and metal contacts for each key.
• 🎉 The clicking sound in mechanical keys comes from the metal contacts hitting each other when the key is pressed.
• 🛠️ Mechanical keyboards offer a more tactile feel due to their intricate internal components, which also contribute to their higher cost.
• 📱 Laptop keyboards use a scissor switch mechanism with rubber domes for a lower profile, differentiating them from desktop keyboards.

Q & A

How many critical parts are inside the inexpensive keyboard mentioned in the script?

The inexpensive keyboard has only 8 critical parts inside.

What are the main components of the inexpensive keyboard's key mechanism?

The main components of the key mechanism in the inexpensive keyboard are a rubber sheet with domes under each key and three plastic sheets, with conductive wires printed on the top and bottom sheets.

How does the inexpensive keyboard detect which key has been pressed?

The inexpensive keyboard detects which key has been pressed by bridging the connection between the top and bottom plastic sheets when a key is pressed, allowing a 3-volt signal to travel from the bottom sheet, through the pressed key, to the top sheet, and back to the microprocessor.

What is a keyboard matrix and how does it relate to the inexpensive keyboard?

A keyboard matrix is a grid-like organization of the keyboard's traces, with the bottom traces forming columns and the top traces forming rows. The inexpensive keyboard uses this matrix to determine which key is pressed by correlating the active column with the input row.

How does the inexpensive keyboard solve the problem of identifying which key is pressed when multiple keys are pressed simultaneously?

The inexpensive keyboard solves this problem by sending a cycle of pulses that turn off one column at a time to determine which key in a row is pressed, with these pulses sent for 65 microseconds to each column, once every 4 milliseconds.

What is the purpose of the 2.4 gigahertz transceiver in the inexpensive keyboard?

The 2.4 gigahertz transceiver in the inexpensive keyboard is used to send the data about which keys are pressed to the connected device using the printed planar antennas.

What is the main difference between the inexpensive keyboard and the mechanical keyboard discussed in the script?

The main difference is that the mechanical keyboard has a more complex and durable key mechanism with a tactile feel and a clicking sound, whereas the inexpensive keyboard uses a simpler and less expensive mechanism with rubber domes.

What is the function of the stem and slider in the mechanical keyboard's key mechanism?

In the mechanical keyboard's key mechanism, the stem and slider work together to move one of the metal contacts away from the other when a key is pressed, creating a connection and causing a click sound. When the key is released, the spring pushes everything back up, separating the metal contacts.

Why are mechanical keyboards more expensive than the inexpensive keyboards?

Mechanical keyboards are more expensive due to the larger printed circuit board and the intricate mechanism inside each key, which provides a more tactile feel and a clicking sound when pressed.

What is the purpose of the scissor switch mechanism in laptop keyboards?

The scissor switch mechanism in laptop keyboards allows for a lower profile while still providing a key mechanism with rubber domes, making it suitable for the thinner design of laptops.

How does the inexpensive keyboard's design highlight the importance of engineering in cost reduction?

The inexpensive keyboard's design highlights the importance of engineering in cost reduction by using only 8 critical parts and a simple key mechanism, allowing the keyboard to be produced and sold at a very low cost while still being functional and durable.