Respond more precisely to your hand movements. The photocell has a lens in front of it that magnifies the reflected light, so the mouse can The light bounces straight back up off the desk into aĪlso mounted under the mouse, a short distance from the LED. (light-emitting diode) mounted on the bottom of the mouse. It shines aīright light down onto your desk from an LED Note how the rubber ball you'd find in a ball-wheel mouse has been replaced by the photocell and LED.Īn optical mouse works in a completely different way. Photo: An optical mouse seen from underneath. One solution is to keep taking your mouse to pieces and cleaning it Īnother option is to get yourself an optical mouse. Up dirt, so the x- and y-axis wheels turn erratically and make the Mouse mat but, even if you have one, the rubber ball and its rollers gradually pick There are various problems with mice like this. US Patent 4,464,652: Cursor control device for use with display systems. For more detail of how this kind of encoding works, take a look at Apple's early 1980s mouse patent By comparing the order in which the two beams are blocked and unblocked, the mouse's circuitry can figure out which way your hand is moving. As the spoked wheel rotates, it partly blocks one emitter-detector beam as it uncovers another. can it? Yes! There are, in fact, two emitters and two detectors side by side. Just counting how many times the light beam is broken, it can't tell the difference between moving 5cm to the leftĪnd 5cm to the right. So the mouse can figure out how far you've moved it, but how does it know which direction it's moved in? If it's You can see a bigger version of this photo on our Flickr page. Generates a sequence of pulses that can be used to measure how much the mouse has moved. As the heavy rubber ball moves, it makes the wheel turn, so its spokes break the beam. On the other side, there's a photoelectric cell (light detector) that LED (light emitter) that generates an infrared beam. Photo: A ball mouse detects movements by using a wheel with spokes Software in your computer moves the cursor on Sends details down the cable to your computer. The counting and measuring is done by the microchip inside the mouse, which The number of times the beam is broken is a way of precisely measuring how far the wheel has turned and The more the wheel turns, the more times the beam is broken. Up of plastic spokes and, as it turns, the spokes repeatedly break a light beam. And if you move the mouse at an angle, the ball Up, only the y-axis wheel turns if you move to the right, only the How do the wheels measure distance?Īs you move the mouse, the ball moves the rollers that turn one or both of the wheels. Y-axis on graph/chart paper) the other detects side-to-side movements (like the x-axis on graph paper). One of the wheels detects movements in an up-and-down direction (like the Thin wheels (numbered 6 and 7 in the photo). Rolls under its own weight and pushes against two plastic rollers linked to How does a mouse like this actually work? As you move it across your desk, the ball
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