Wednesday, August 26, 2015
`
`iPod click wheel
`
`From Wikipedia, the free encyclopedia
`
`The iPod click wheel is the navigation component of several iPod models. It uses a
`combination of touch technology and traditional buttons, involving the technology of
`capacitive sensing, which senses the capacitance of the user's fingers. The wheel allows a user
`to find music, videos, photos and play games on the device. The wheel is flush on the face of
`the iPod and is located below the screen.
`
`The design was first released with the iPod Mini, and was last used with the iPod Classic.
`
`Contents
`◾ 1 Details
`◾ 2 Lawsuits
`◾ 3 References
`◾ 4 External links
`
`Details
`
`The iPod line's signature click
`wheel
`
`The click wheel detects a user's input via its touch sensitive ring. Because of four mechanical buttons that lie beneath it, the ring is
`able to perform multiple commands.[1] For example, browsing through music, after selecting a particular song, the click-wheel is
`used to adjust the volume. Pressing the select button can be used to skip to a specific part in the song.
`
`The primary technology that the click-wheel demonstrates is that of Capacitive sensing. This technology actually dates back to 1919,
`where it was first utilized in a musical instrument called a Theremin. It allowed the pitch and volume of the instrument to be
`controlled by the distance from the musician's hands to two antennae. When two metal plates are placed very close to one another,
`without coming into contact, a current passes through the plates, energy is stored, but once the current is taken away, the stored
`energy creates a current on its own. This is how a capacitor gathers and stores energy.[2]
`
`This same principle is applied to the iPod Classic and on the first through fifth generations of the iPod Nano.
`
`The "brain" behind the click-wheel is the conductive membrane behind the plastic covering. This membrane has "channels" that
`when connected, create a set of coordinates. These channels are conductors, which when connected to another conductor (a finger in
`this case), try to send a current through the user's finger, but are blocked by the plastic covering the click-wheel. So instead of
`passing through the plastic, the current creates a charge at the closest location to the finger, which is also known as capacitance. The
`component that detects this change in capacitance is the controller. Whenever the controller senses a change, it sends a signal to the
`microprocessor, which performs the desired action. The faster a finger moves around the wheel, the more concentrated the stream of
`signals it sends out. The moment the finger leaves the wheel, however, is when the controller stops detecting change in capacitance,
`therefore stopping the current process.[1]
`Lawsuits
`
`It is not widely known that Apple did not develop the click wheel; Synaptics came up with the design for the device.[3] There have
`nevertheless been a few lawsuits concerning its capacitance-sensing technology.
`References
`
`1. Layton, Julia. "How iPods work." (http://electronics.howstuffworks.com/ipod4.htm) How Stuff Works March 14, 2006 (accessed October
`12, 2008).
`
`https://en.wikipedia.org/wiki/IPod_click_wheel
`
`

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`Wednesday, August 26, 2015
`2. Wimmer, Raphael; Kranz, Matthias; Boring, Sebastian; Schmidt, Albrecht (2007). "A Capacitive Sensing Toolkit for Pervasive Activity
`Detection and Recognition" (http://www.ibr.cs.tu-bs.de/users/kranz/papers/Kranz-
`ACapacitiveSensingToolkitForPervasiveActivityDetection-PerCom2007.pdf) (PDF). PERCOM '07: Proceedings of the Fifth IEEE
`International Conference on Pervasive Computing and Communications. IEEE International Conference on Pervasive Computing and
`Communications (PerCom) (http://www.percom.org/). IEEE Computer Society. pp. 171––180. doi:10.1109/PERCOM.2007.1
`(https://dx.doi.org/10.1109%2FPERCOM.2007.1). ISBN 0-7695-2787-6.
`3. Hurst, Wolfgang. "A Study of Algorithms in Mobile Devices" (http://portal.acm.org/citation.cfm?
`id=1227368&coll=GUIDE&dl=GUIDE&CFID=6187803&CFTOKEN=40286539&ret=1#Fulltext) March 2007 Click Wheel Study
`(accessed October 12, 2008).
`External links
`
`Retrieved from "https://en.wikipedia.org/w/index.php?title=IPod_click_wheel&oldid=673629844"
`
`Categories: IPod
`◾ This page was last modified on 29 July 2015, at 12:59.
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`
`https://en.wikipedia.org/wiki/IPod_click_wheel