Apple Patents: Rotary Mouse

The patent describes the disadvantages of the traditional scroll wheel mouse:

Unfortunately, the mouse described in FIG. 1 [Traditional Scrollwheel mouse] has several drawbacks. For example, the scroll wheel is limited in that it only provides a single finger position for accessing the scroll wheel (e.g., same position for left and right handed users). Furthermore, because only a small portion of the wheel can be used at any one time, the user cannot continuously turn the wheel. That is, the user must scroll, pick up a finger, scroll, pick up a finger, etc. This takes time and can be an annoyance to a user. In addition, because a portion of the wheel protrudes above the top surface of the mouse, inadvertent or accidental scrolling may occur when one of the two buttons is activated. That is, when the user goes to push the button or when the user switches from one button to the other, the user's finger may also engage the scroll wheel thus causing the wheel to turn when the button is depressed. Moreover, because the scroll wheel can only be manipulated in one direction, the use of the scroll wheel becomes counter intuitive when scrolling in a different direction in the GUI, as for example directions that are orthogonal thereto. That is, the scroll wheel only moves in one direction and thus it generally corresponds well to vertical scrolling and not horizontal scrolling (or vice versa). Also, the protruding scroll wheel is not aesthetically pleasing and thus it presents industrial design difficulties.

Users have speculated about such a wheel-device on a mouse, since the release of the iPod, with at least one mockup posted in May 2002.