A developer unit (210, 310, 610) usable with a liquid electrophotographic printing apparatus having a photosensitive drum, the developer unit (210, 310, 610) comprising: a developer roller configured to receive ink, and to selectively engage and rotatably transfer the ink to the photosensitive drum, the developer roller configured to switch between a contact mode in contact with the photosensitive drum when the developer roller is rotating and a non-contact mode out of contact with the photosensitive drum when the developer roller is not rotating; a squeegee roller selectively in contact with the developer roller, the squeegee roller configured to at least condense the received ink on the developer roller in the contact mode, and configured to be apart from the developer roller in the non-contact mode; and a cleaner roller selectively in contact with the developer roller, the cleaner roller configured to remove remaining ink from the developer roller not transferred to the photosensitive drum in the contact mode, and to be apart from the developer roller in the non-contact mode; wherein at least one of the squeegee roller, the cleaner roller and the developer roller are configured to move between the contact mode and the non-contact mode in response to a rotational state of the developer roller; the developer unit further comprising a cap member configured to move between a cover position in which the cap member covers an exposed portion of the developer roller opposite the photosensitive drum and an uncover position in which the cap member uncovers the exposed portion of the developer roller, wherein the cap member is configured to move between the cover position and the uncover position in response to the rotational state of the developer roller. a developer roller configured to receive ink, and to selectively engage and rotatably transfer the ink to the photosensitive drum, the developer roller configured to switch between a contact mode in contact with the photosensitive drum when the developer roller is rotating and a non-contact mode out of contact with the photosensitive drum when the developer roller is not rotating; a squeegee roller selectively in contact with the developer roller, the squeegee roller configured to at least condense the received ink on the developer roller in the contact mode, and configured to be apart from the developer roller in the non-contact mode; and a cleaner roller selectively in contact with the developer roller, the cleaner roller configured to remove remaining ink from the developer roller not transferred to the photosensitive drum in the contact mode, and to be apart from the developer roller in the non-contact mode; wherein at least one of the squeegee roller, the cleaner roller and the developer roller are configured to move between the contact mode and the non-contact mode in response to a rotational state of the developer roller; the developer unit further comprising a cap member configured to move between a cover position in which the cap member covers an exposed portion of the developer roller opposite the photosensitive drum and an uncover position in which the cap member uncovers the exposed portion of the developer roller, wherein the cap member is configured to move between the cover position and the uncover position in response to the rotational state of the developer roller.