The present invention relates to a built-in flash mechanism that will pop up
when the illumination is insufficient or it is manually switched on. The present
invention comprises a flash unit having a buckle, a driving motor, a driving gear
set formed on said driving motor, a axle wheel portion having a clip, a driven
gear set formed on said axle wheel portion, a light-sensitive sensor, and a pusher
for obstructing light into said light-sensitive sensor. When the light is obstructs
by the pusher, the sensor will activate the driving motor to release the flash
device or lock the flash unit at a receiving chamber.