IPod Click Wheel
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 energy 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 directly underneath the screen.
The design was first released with the iPod Mini
, and is now only currently used on the iPod Classic
.
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.
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.
came up with the design for the device. There have nevertheless been a few lawsuits concerning its capacitance-sensing technology.
In January of 2007, a U.K Based company named Quantum Research made public a lawsuit against Apple claiming that its own patents on this technology were being infringed by Apple. Legal action regarding this lawsuit had been going on since 2005, but was not made public until two years after.
IPod
iPod is a line of portable media players created and marketed by Apple Inc. The product line-up currently consists of the hard drive-based iPod Classic, the touchscreen iPod Touch, the compact iPod Nano, and the ultra-compact iPod Shuffle...
click wheel is the navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
component of several iPod models. It uses a combination of touch technology and traditional buttons, involving the technology of capacitive sensing
Capacitive sensing
In electrical engineering, capacitive sensing is a technology based on capacitive coupling that is used in many different types of sensors, including those to detect and measure: proximity, position or displacement, humidity, fluid level, and acceleration...
, which senses the energy 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
IPod
iPod is a line of portable media players created and marketed by Apple Inc. The product line-up currently consists of the hard drive-based iPod Classic, the touchscreen iPod Touch, the compact iPod Nano, and the ultra-compact iPod Shuffle...
and is located directly underneath the screen.
The design was first released with the iPod Mini
IPod mini
The iPod Mini is a digital audio player designed and marketed by Apple Inc. It was the midrange model in Apple's iPod product line. It was announced on January 6, 2004 and released on February 20 of the same year. A second-generation version was announced on February 23, 2005 and released later...
, and is now only currently used on the iPod Classic
IPod classic
The iPod Classic is a portable media player marketed by Apple Inc...
.
Details
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. 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
Theremin
The theremin , originally known as the aetherphone/etherophone, thereminophone or termenvox/thereminvox is an early electronic musical instrument controlled without discernible physical contact from the player. It is named after its Russian inventor, Professor Léon Theremin, who patented the device...
. 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.
This same principle is applied to the iPod Classic
IPod classic
The iPod Classic is a portable media player marketed by Apple Inc...
and on the first through fifth generations of the iPod Nano
IPod nano
iPod Nano is a digital media player designed and marketed by Apple Inc.. The first generation of iPod Nano was introduced on September 7, 2005 as a replacement for iPod Mini. It uses flash memory for storage. iPod Nano has gone through six models, or generations, since its introduction...
.
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
Capacitance
In electromagnetism and electronics, capacitance is the ability of a capacitor to store energy in an electric field. Capacitance is also a measure of the amount of electric potential energy stored for a given electric potential. A common form of energy storage device is a parallel-plate capacitor...
, therefore stopping the current process.
Lawsuits
It is not widely known that Apple did not develop the click wheel; SynapticsSynaptics
Synaptics develops human interface solutions for many major consumer electronics companies, such as Apple Inc., Asus, Acer, Dell, Gateway, HP, HTC, Lenovo, LG, Logitech, Nokia, Samsung, Sony, Sony Ericsson, Toshiba and several others...
came up with the design for the device. There have nevertheless been a few lawsuits concerning its capacitance-sensing technology.
In January of 2007, a U.K Based company named Quantum Research made public a lawsuit against Apple claiming that its own patents on this technology were being infringed by Apple. Legal action regarding this lawsuit had been going on since 2005, but was not made public until two years after.