| 摘要 |
PURPOSE:To prevent an image defect and obtain sufficient image concentration by making a waveform of A.C. bias voltage, applied to a developer carrier, a convex curve in which a rise in a development promoting direction is shorter than a fall in a development restraining direction. CONSTITUTION:A device is composed of a developing roll 2 arranged facing to an electrostatic latent image carrier 4, and a developer regulating member 3 arranged so that a tip part can pressedly contact the roll 2, and the roll 2 and the member 3 are arranged in a hopper 1 housing magnetic toner 10. Also an A.C. high voltage power source 5 and a D.C. power source 6 for applying developing bias voltage are connected to the roll 2. In the A.C. voltage, a relation of TR>=TF is satisfied where TF: rise or fall time of voltage in a development promoting direction and TR: fall or rise time of voltage in a development restraining direction, and an A.C. voltage waveform at TR is made a convex curve projecting in a development promoting direction. This causes the waveform of developing bias voltage to have a sawteeth state to effectively prevent forming a toner chain, and a developing actual value can be improved. |
