How Does a Computer Mouse Work?

Video Transcript

"Hi, my name is Dave Andrews. Today I'm going to show you how a computer mouse works. I'm first going to explain to you how a ball mouse works, and then I'm going to show you a little bit of how an optical mouse works. Let's go to our computer. I'm going to pull up this diagram here. This is a basic ball mouse, kind of viewed from a cross section. This little green circle here is the ball that's in the bottom of your mouse. Now, as you move the mouse across the surface, basically either in the X plain or in the Y plain, right here, rather this would be the X plain and that would be the Y plain. The ball that's inside of the mouse rotates. Now, attached to that little ball, right here, kind of rubbing up against it, is a tiny little roller that rolls along with the ball, so as this ball rolls, kind of like a gear, it'll also turn this roller, which will turn this larger roller that has a tiny device that detects that roller as it's rolling. So since this ball is rolling, this smaller gear is rolling and turning this larger gear, this electronic device will notice that that that large gear is turning, and will register that and send that as a movement through this mouse cable up to your computer. Now this other wheel over here basically does the other axis as the wheel turns, basically if you're moving your mouse up or down, one of these rollers will get that movement, if you're moving your mouse left or right, the other roller will pick up that movement and transmit those changes. Now I have here an optical mouse that I'm going to show you as well, which acts a little bit differently. As you can see in the optical mouse you can tell one is optical when you look at the bottom, it'll have a red kind of laser light coming out of it, and you can sort of see that reflection there in my hand a little bit. Basically the difference between an optical mouse and a ball mouse is that this uses a very low power laser which beams out across the surface that the mouse is sitting on. Now, lasers are reflective, so as it's beaming out and hitting the surface that it's sitting on, that laser will then reflect back to a sensor inside of the mouse. And that sensor will detect the changes in the layout of the surface that it's laying on. You know basically textures in the wood of your desk for instance, it'll notice that those textures are changing which means it's detecting that the mouse has been moved. My name is Dave Andrews, and I've just explained to you how a mouse works."