A proportional force input apparatus for an electronic device includes a
mechanism operable by a user of the electronic device, such as a stylus
inserted into a spring-loaded socket of the device. The mechanism
provides a tactile feedback to the user proportional to a force applied
by the user. A variable strength sensor detects the force applied by the
user to the mechanism and converts this to an electrical signal
proportional to the force applied by the user. A processor operates to
input the electric signal from the variable strength sensor and provide
force information to an application running on the electronic device.
Optionally, a second sensor can detect rotation of the stylus. As a
result, a stylus can be used to provide vector information to an
application such as a game.