IMAGE FORMATION APPARATUS

To achieve both of the reduction in the cost of a development power source circuit which generates the development bias voltage obtained by overlapping the DC voltage on the AC voltage and the reduction in the power consumption.SOLUTION: An image formation apparatus which performs image formation by using plural colors of toner comprises a photoreceptor drum, a development device, and a development power source circuit which applies the development bias voltage to the development device. The development device comprises a plurality of development rollers corresponding to the plural colors of toner. The development power source circuit comprises: one AC power source circuit 11 which generates the AC voltage; a plurality of DC power source circuits 12 which generate the DC voltage corresponding to the plural colors of toner; a plurality of overlapping capacitors C1-C4 which overlap the AC voltage on each DC voltage generated by the plurality of DC power source circuits at a prescribed overlapping point; and an AC cut-off switch SW1 which conducts or cuts off the AC voltage. The AC cut-off switch is arranged between an output terminal of the AC voltage generated by the AC power source circuit and the overlapping capacitor for a color other than the black.SELECTED DRAWING: Figure 5 【課題】直流電圧に交流電圧を重畳した現像バイアス電圧を発生させる現像電源回路の低価格化と、消費電力の削減の両方を実現することを課題とする。【解決手段】複数色のトナーを利用した画像形成を行う画像形成装置であって、感光体ドラムと、現像装置と、現像装置に現像バイアス電圧を印加する現像電源回路とを備え、現像装置が、トナーの複数色に対応した複数の現像ローラを備え、現像電源回路が、交流電圧を発生させる１つの交流電源回路１１と、トナーの複数色に対応した直流電圧を発生させる複数の直流電源回路１２と、所定の重畳点で、交流電圧を、複数の直流電源回路によって発生された各直流電圧に重畳するための複数の重畳コンデンサＣ１−Ｃ４と、交流電圧を通電または遮断する交流遮断スイッチＳＷ１とを備える。交流遮断スイッチは、交流電源回路によって発生された交流電圧の出力端子と黒色以外の他色用の重畳コンデンサとの間に配置される。【選択図】図５