A sector drive mechanism includes an electromagnetic actuator including a
rotor having four polarities, a C-shaped stator, and a current control
portion that controls current applied to a first coil and a second coil,
the C-shaped stator including a first magnetic pole magnetically excited
by the first coil, a second magnetic pole magnetically excited by the
second coil, and a third magnetic pole magnetically excited by the first
coil and the second coil, and sectors that are connected to the
electromagnetic actuator to open and close a shutter opening provided in
a substrate. The first coil and the second coil are driven to close the
shutter opening with a fewer number of pulses applied from the current
control portion than the number of the pulses to open the shutter
opening.