3 ms·
Yes, that's right. The little rollers were on an axle that extended a bit further terminating into a spoked disk which sat in the middle of an optical detector
by dammitcoetzee 12y ago
Yes, that's right. The little rollers were on an axle that extended a bit further terminating into a spoked disk which sat in the middle of an optical detector and emitter pair. It used some tricks to figure out when the mouse was going forward and when it was going backward (quadrature), but mostly it just counts the pulses of light it sees and turns that into displacement coordinates.
EDIT:
Wikipedia has a pretty good picture of this and a better explanation:
http://en.wikipedia.org/wiki/Mouse_(computing)#Mechanical_mice http://en.wikipedia.org/wiki/Mouse_(computing)#Mechanical_mi...
- JoeAltmaier 12y agoI thought the holes in the disk were in Grey code? Maybe that reduces to quadrature in small cases
- joezydeco 12y agoThe encoder disc is really a 1-dimensional input. Adding a second opto-detector that is one half-bit out of phase gives you two simultaneous inputs and yes, it comes out to a 2-bit Grey code. 00 -> 01 -> 11 -> 10 -> 00
- dammitcoetzee 12y agoQuadrature is a gray code with two offset spoke sets so that you can tell direction and rotation by which pulse precedes the other. http://www.ni.com/white-paper/4763/en/ http://www.ni.com/white-paper/4763/en/