Image reader and image forming apparatus including the image reader

An image reader, comprising an all-in-one optical scanning unit that moves in a sub-scanning direction orthogonal to a main scanning direction to read an original image on an original document sheet,

• the optical scanning unit comprising:
• a housing that houses a reading device to read light reflected by the original document sheet;
• a lighting device detachably attached to the housing to emit light toward the original document sheet;
• a shield member detachably attached to the housing to shield the reading device from the lighting device to form a space for the reading device inside the housing, the shield member guiding the light reflected by the original document sheet to the space for the reading device;
• a first positioner provided in the housing;
• and
• a second positioner provided on the shield member to engage the first positioner provided in the housing to position the reading device with respect to the lighting device,
• the lighting device comprising:
• a light source to emit light;
• and
• a reflection member integrally provided on the shield member to reflect the light emitted by the light source toward an irradiation region on the original document sheet.

An image reader, comprising means for scanning an original image on an original document sheet by moving in a sub-scanning direction,

• the means for scanning comprising:
• means for covering the means for scanning;
• means for irradiating the original document sheet by emitting light toward the original document sheet, detachably attached to the means for covering;
• means for reading the light reflected by the original document sheet, provided inside the means for covering;
• means for shielding the means for reading from the means for irradiating, the means for shielding being detachably attached to the means for covering to form a space for the means for reading inside the means for covering;
• means for guiding the light reflected by the original document sheet to the space containing the means for reading, the means for guiding having a slit shape and provided in the means for shielding to extend in a main scanning direction;
• first means for positioning the means for reading with respect to the means for irradiating, provided in the means for covering;
• and
• second means for positioning the means for reading with respect to the means for irradiating by engaging the first means for positioning provided in the means for covering, provided on the means for shielding,
• the means for irradiating comprising:
• means for emitting light;
• and
• means for reflecting the light emitted by the means for emitting toward an irradiation region on the original document sheet, the means for reflecting being integrally provided on the means for shielding.