Abstract: An image forming apparatus including: an image bearing member; an optical unit for image exposure of the image bearing member, the optical unit being mountable from a side of the apparatus main body; and an elastic member for pressuring the optical unit downward.

Abstract: A process cartridge detachably mountable to an image forming apparatus includes an image bearing member; process device actable on the image bearing member; a first frame containing the image bearing member and the process device; and a second frame engageable with and disengageable from the first frame and containing a developer container.

Abstract: Changes in toner developability of toners in a liquid toner system are determined and compensated for by sensing the toner concentration and liquid toner volume in a tank, based on changes in the toner concentration and toner mass in the tank. Based on the foreground areas for a color separation layer corresponding to a particular toner, the developed area for that toner for one or more printed pages can be determined. From the developed area and the consumed mass of toner, a developed mass per unit area (DMA) can be determined. Based on the determined DMA, the sensed toner concentration and a voltage differential, the developability of the toner can be determined. Based on a target DMA, the sensed toner concentration and the determined developability of the toner, a new voltage differential can be determined.