Developing device capable of reliably charging developing agent
AssigneeBrother Kogyo Kabushiki Kaisha
InventorKazumasa Makino
Life of this patent
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Abstract
A developing unit includes a photosensitive drum, a developing drum, and an agitator. When a charge of toner has dropped below a predetermined charging amount before a subsequent image forming operation starts, a pre-driving operation is performed so that the developing drum and the agitator are rotated before a sheet feed operation starts. Therefore, sufficient charge can be applied to the toner before a developing operation starts, thereby providing a high-quality image. Also, because the photosensitive drum and the developing roller are separated from each other during the pre-driving operation, the photosensitive drum and the developing roller are prevented from being worn down.
Claims25
A developing device used in an image forming device including a feeding mechanism that feeds a recording medium, comprising:
- a photosensitive member;
- a developing agent chamber housing a developing agent;
- a developing unit that selectively supplies the developing agent housed in the developing agent chamber to the photosensitive member;
- a contact/separating mechanism that selectively contacts and separates the photosensitive member and the developing unit;
- and
- a driving member that drives the developing unit, wherein the contact/separating mechanism separates the photosensitive member and the developing unit from each other when the driving member starts driving the developing unit before the feeding mechanism starts feeding the recording medium.
A developing device, comprising:
- a photosensitive member;
- a developing agent chamber housing a developing agent;
- a developing unit that supplies the developing agent housed in the developing agent chamber to the photosensitive member;
- a contact/separating mechanism that selectively contacts and separates the photosensitive member and the developing unit;
- a judging unit that judges whether a charging amount of the developing agent is sufficient or insufficient;
- and
- a driving member that drives the developing unit in a condition where the photosensitive member and the developing unit are being separated from each other, wherein when the judging unit judges that the charging amount of the developing agent is insufficient, the driving member drives the developing unit for a time duration longer than when the judging unit judges that the charging amount of the developing agent is sufficient.
An image forming device for performing an image forming operation, comprising:
- a feeding mechanism that feeds a recording medium;
- a photosensitive member;
- a developing agent chamber housing a developing agent;
- a developing unit that selectively supplies the developing agent housed in the developing agent chamber to the photosensitive member;
- a contact/separating mechanism that selectively contacts and separates the photosensitive member and the developing unit;
- and
- a driving member that drives the developing unit, wherein when the contact/separating mechanism separates the photosensitive member and the developing unit from each other when the driving member starts driving the developing unit before the feeding mechanism starts feeding the recording medium.
An image forming device comprising:
- a photosensitive member;
- a developing roller that selectively supplies toner to the photosensitive member;
- a separating mechanism that separates the photosensitive member and the developing roller from each other;
- a rotating mechanism that rotates the developing roller in a condition where the photosensitive member and the developing roller are being separated from each other;
- and
- a control unit that controls the rotation of the developing roller in accordance with a time duration from an end of a previous image forming operation to a start of a subsequent image forming operation.
An image forming device comprising:
- a photosensitive member;
- a developing roller that selectively supplies toner to the photosensitive member;
- a separating mechanism that separates the photosensitive member and the developing roller from each other;
- a rotating mechanism that rotates the developing roller in a condition where the photosensitive member and the developing roller are being separated from each other;
- and
- a control unit that controls the rotation of the developing roller in accordance with a charging amount of the toner.
Dependencies are inferred from the claim text.