Original reader, optical module, and optical reading method

An original reader comprising a module including, as integral constituents, a light source for illuminating an original, a contracting optical system having a lens and a mirror and a line sensor, for reading out original surface data by performing main scanning to linearly scan the original with the line sensor and auxiliary scanning to mechanically scan the module in directions normal to the main scanning directions, wherein:

• the contracting optical system comprises a first optical system and a second optical system;
• the module includes the first optical system and a metal sheet frame, the metal sheet frame extending parallel to the auxiliary scanning directions, the first optical system being positioned and secured to a flat part of the frame;
• and
• the light path of the contracting optical system is reciprocated a plurality of times on the side closer to the original surface on the flat part of the frame in the first optical system constituted by a plurality of mirrors before penetrating an opening in the frame flat part and being led to a second optical system disposed more apart from the original surface of the frame flat part and constituted by a lens, a CCD and a mirror,
• wherein the metal sheet frame is arranged inside the module and is disposed between the first optical system and the second optical system,
• wherein a drive source for driving the module in the auxiliary scanning direction is secured to the flat part of the frame such that a drive gear of the drive source penetrates a notch formed in the frame flat part and the drive gear of the drive source transfers the drive power of the drive source via the shaft of a transfer gear for the transfer, the transfer gear shaft being provided on the frame flat part on the side thereof opposite the drive source, and
• wherein the flat part of the frame has a slide member corresponding to a rail for guiding the module in the auxiliary scanning directions.