Editing Mouse (section)

===Opto-mechanical===
Historically, most mice have used an [[opto-mechanical sensor]], which drive a pair of perpendicular, relative [[rotary encoder]]s using a heavy, rubber-coated ball. The ball rolls across the tracking surface within an exposed enclosure, driving rollers connected to the rotary encoders; a third roller, which is spring-loaded, keeps the ball pressed against the sensor rollers and away from the ball enclosure.

Dust and lint from the tracking surface is picked up by the ball and deposited on the rollers, causing tracking to become erratic. Periodically, the ball enclosure must be opened, the ball removed, and the compacted dirt scraped from the rollers. Cheaper mice also suffer from wear of the roller surface, which also adversely affects tracking.

The diagonal pressure roller is also subject to wear and damage; if the pressure roller loses strength, the mouse will seize solid when moved in the direction of the roller, as the ball will come into contact with the inside wall of its enclosure and lock its motion through friction.

Opto-mechanical mice are very similar to opto-mechanical [[trackball]]s: either is simply an inverted version of the other.

See: [[:Category:Opto-mechanical mice|Opto-mechanical mice]]