| 摘要 |
PURPOSE: To collect an unnecessary developer not used for printing and supply a fresh developer at all times, by setting voltage to be impressed to a first and a second electrodes and a developer feed roller to satisfy a specific relation in a developer recovery mode. CONSTITUTION: A toner is supplied to the side of a first electrode 21 by an electric field between a developer (toner) feed roller 1 and the first electrode 21 in a printing head 2. The toner is allowed to pass through a toner penetration hole due to an electric field between the first and a second electrodes 21 and 22 and blown to a recording paper P transferred via a base roller (base electrode) 3 and a fixing roller 4, whereby printing is achieved. Supposing that voltages impressed to the electrodes 21, 22 and roller 1 are V1R, V2R and VSR respectively, the apparatus controls to impress a constant voltage to satisfy V2R<V1R<VSR if a developer is charged with a negative polarity in a developer recovery mode and V2R>V1R>VSR if the developer is charged with a positive polarity. |
