How do touchscreens work? | Summary and Q&A

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October 6, 2016
by
Physics Girl
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How do touchscreens work?

TL;DR

This video explores how your phone transmits your touch into an electrical signal to display an emoji on the screen.

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Key Insights

  • 🕵️ Mutual capacitance sensing is a technology used in smartphones to accurately detect touch.
  • 📣 The disruption of charge equilibrium on the phone screen when touched changes the electrical signal.
  • 👨‍💻 Computer chips manipulate the signal into binary code, which is then translated into Unicode to display the desired character.

Transcript

Hi, there. I'm Diana, and I was just thinking how cool is it that a random series of taps and swipes on your phone can end up sending a thoughtful message to your mom? How does your phone do that? Like, what exactly happens that a tiny adorable cartoon shows up on your phone and is transmitted thousands of miles away and shows up on somebody else'... Read More

Questions & Answers

Q: How does your phone transmit your touch into an electrical signal?

When your finger touches the screen, the charge distribution on the phone is disrupted, causing a change in the electrical signal. This signal is then transmitted to the phone's computer chip.

Q: What technology is used to sense touch on smartphones?

Most smartphones use mutual capacitance sensing, which is more accurate and sensitive than other technologies. It involves tiny conductors called electrodes arranged in a diamond grid underneath the glass surface of the phone.

Q: Can you use materials other than your finger to touch the screen?

Yes, as long as the material is conductive and has a sufficiently large surface area. For example, you can use the back of a metal spoon or even a hot dog to text, but materials like wool gloves or a metal safety pin won't work.

Q: How does the phone know which pixels to light up to display the emoji?

Once the computer chip receives the digital signal from the touchscreen, it manipulates the signal into a series of 32 pulses of voltage. These pulses trigger transistors that direct current to turn on the pixels corresponding to the emoji.

Summary & Key Takeaways

  • When you touch your phone screen, you disrupt the charge distribution, causing a change in the electrical signal.

  • The phone's computer chip uses transistors to manipulate the signal into a binary pattern, representing the desired emoji.

  • This binary signal is then translated into human language using Unicode, and the pixels on the screen are directed to display the emoji.

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