An image reading device reads an image of an electronic part as an image
pickup object with camera 8 having a line sensor. The line sensor
comprises a plurality of pixels having a photoelectric transfer element
arranged in series. The image reading device selects pixels periodically
one by one and outputs image signals. The pixels for outputting image
signals are set based on width data of an image pickup area stored on
image pickup area storage 10. The image reading device monitors a relative
positional relation between the image pickup object and the line sensor
using a pulse of encoder 4A, and controls writing of the image signal into
an image storage 15 with a storage controller 12 based on length data of
the image pickup area. This process can remove uselessness of outputting
the image signal from an unnecessary range and storing it, and improve
efficient image reading.
