Imaging unit

An imaging unit comprising:

• a drum unit rotatably supporting a photoreceptor drum;
• a developer unit supported with respect to the drum unit pivotally about a predetermined rotation axis thereof, the developer unit including:
• a casing;
• a developer roller;
• a support shaft having first and second ends and supporting the developer roller for integral rotation therewith;
• first and second spacing regulation sleeves respectively engaged with the first and second ends of the support shaft, and adapted to abut against a circumference of the photoreceptor drum for regulating a spacing between the developer roller and the photoreceptor drum;
• a driven gear provided at the first end of the support shaft for integral rotation therewith;
• a drive transmission gear rotatably supported by the casing for transmitting a driving force to the driven gear;
• a resilient member for pressing the second spacing regulation sleeve against the circumference of the photoreceptor;
• a first member fixed to an end face of the casing of the developer unit and having a support hole;
• and
• a second member supported by the support hole of the first member so as to be slidable radially of the support shaft of the developer roller,
• the first end of the support shaft being rotatably supported in such a manner that radial movement thereof is restricted by the casing of the developer unit,
• the second end of the support shaft being supported by the casing of the developer unit so as to be movable toward and away from the photoreceptor drum, the developer unit being adapted to be biased rotatively about the predetermined axis by the driving force transmitted from the drive transmission gear to the driven gear so that the first spacing regulation sleeve is pressed against the photoreceptor drum
• the second member having a support hole rotatable supporting the second end of the support shaft of the developer roller, and
• the resilient member being interposed between the casing of the developer unit and the second member for biasing the second member toward the photoreceptor drum.