So, as I'm sitting here listening to my MP3 player I'm thinking: These earbuds could be so much smarter. I think that they need to embed a small heat sensor into the actual earpieces so that they could detect whether they are in your ear or not. By using this information the MP3 player could handle common user interactions more completely. For instance, when someone walks up to me and I take my earbuds out, it pauses the music. Or, if I take one of the earbuds out (because I want to hear some ambient noise) the player should switch to mono, and stop wasting energy on that earbud. All of this sounds like something Apple would do on the next iPod. They like these advanced user interactions (and so do I).
Implementation notes
The most difficult part of dealing with this problem is dealing with the existing interface for headphones. You basically have three wires, left, right and ground. How will the heat sensor signal the player? How will the senor get power?
I think that the best solution is one where the switch doesn't use electricity. If you can bind together two metals that expand at different rates, you can get a primitive switch based on the temperature of the metals. This is similar to how the old circular thermostats work (I wouldn't recommend the mercury switch in them though).
To signal back to the player the earbuds can either short out the connection, or hold it at high impedance. Both of these can be detected at the player, but the high impedance situation also corresponds with removing the headphones -- which should have similar user interactions. So, if the player detects no current on one of the headphones, it should assume that it has been disconnected and stop outputting music to it. If both earbuds are in this state, it should pause the music (and probably rewind a couple seconds - the sensors won't be that accurate).
Man, this would be cool.
posted Apr 28, 2005 | permanent link
