Image forming apparatus and image forming method

摘要

A recording head of an image forming apparatus comprises an insulating base, a plurality of ejection electrodes formed on the base, and an ink tank arranged on the upper surface of the base so as to cover the ejection electrodes. An ejection point at the distal end of each ejection electrode projects outside the ink tank through a slit in the ink tank. A grounded platen roller is provided at a position to sandwich a paper sheet with the ejection electrodes. A bias power supply for applying a bias voltage to a certain ejection electrode selected in accordance with an image signal, and a recording voltage generation section for applying a recording voltage to this ejection electrode are connected to the rear ends of the ejection electrodes. The recording voltage consists of an agglomeration voltage for collecting charged coloring material particles at the selected ejection electrode, and an ejection voltage for ejecting the coloring material particles at the selected ejection electrode. When the recording voltage is applied to the selected ejection electrode upon application of the bias voltage to the ejection electrodes, a high-concentration ink droplet ejects.