| 摘要 |
PURPOSE:To obtain electrostatic images of high quality by arranging a lock lever on the revolving shaft of a developing roller and allowing force, which acts at the time of rotating and driving the developing roller, to act in the vertical direction and keeping the facility of attachment and detachment and suppressing the vibration of the developing roller. CONSTITUTION:A gear 74 in the shaft end of a developing roller 26 is engaged with a driving gear 96 of the developing roller, and force P from the gear 96 to the gear 74, namely, the roll 26 acts in the vertical direction when the gear 74 is driven by the gear 96. Meanwhile, not only the gear 74 but also a lock lever 101 is rotatably attached to the shaft of the roller 26, and the upward force is applied to this lever 101 by a tension spring 102. When a developing unit 59 is set in a prescribed position, the lever 101 depressed by a flat spring 103 provided on a printer upper unit and is caught by a lock pin 105 to restrict the movement in the vertical direction of the unit 59. Since the force P acting upon the roller 26 is only in the vertical direction and the vertical movement of the unit 59 is restricted by the lever 101, the contacting pressure between the roll 26 and a photosensitive body 11 is stabilized to reduce the vibration of the roller 26.
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