The traditional way of removing an iPod or iPhone from your computer system after connecting to iTunes is to use the eject option shown here. You do this procedure so that the operating system can perform a needed dismount operation (e.g. finish read/write transactions, close files etc) to prevent data loss when the device is disconnected from the host system.  

According to Apple, a common problem with conventional dismount procedures is that users often forget to follow the dismount procedures. For users who remember to use the proper dismount procedures, there is often a long wait while the operating system performs dismount operations. This wait can be several seconds long which can be frustrating to many users.

The Solution

The solution according to Apple is to enable the USB cable connector to sense an impending touch by the user. Responsive to the signal, the host system automatically initiates one or more operations related to disengaging the portable device from the host system. Such a feature will allow a user to disconnect the portable device from the host system more quickly, and also prevents data corruption due to failure of the user to follow proper procedures.

System Overview

Apple's patent FIG. 1 shown below is a block diagram of example system 100 which can include host system 102, a portable device 104 and touch sensor 106.

In the example shown, touch sensor 106 can be a capacitive-sensing system, which includes sensor 108 (e.g., a Pyrex.RTM. glass overlay) mounted on printed circuit board (PCB) 110 (e.g., made from FR4 material). PCB 110 can include conductors 114 for generating fringing electric fields. Placing a finger near a fringing electric field adds conductive surface area to the capacitive-sensing system. The finger's capacitance adds additional charge storage capacity to the capacitive-sensing system which can be detected. Printed circuit traces 112 (e.g., copper traces) can electrically connect conductors 114 to an energy source. Traces 112 can be designed to direct the fringing fields into sensor 108, so the fringing fields are accessible by one or more fingers of a user. In some implementations, the fringing fields can be designed to allow touch detection when the user's finger is proximate sensor 108 but not actually touching sensor 108. This allows detection of an impending touch.

In some implementations, when the host system receives or detects the touch signal, the host system performs (e.g., automatically) one or more operations on the host system and/or the device. Some examples of operations can include completing transactions (e.g., read/write requests to the device), closing applications or files, generating and presenting visual or audio feedback warnings to the user to wait for the operations to complete before disconnecting the device, etc. If the operations are complete (306), the portable device can be disengaged (e.g., automatically, electrically, optically, magnetically, physically) from the host system so that the user can safely remove the device.