| 摘要 |
PURPOSE:To prevent the lowering of the picture quality, by performing a soft development with use of a unicomponent developer when a double-color development is performed with a developer of two colors charged in the polarities opposite to each other. CONSTITUTION:For the two electrostatic latent images of opposite polarities to each other which are formed on a latent image carrier, a red toner charged in the negative polarity is supplied first to the latent image corresponding to the red color of positive polarity from the 1st developing devie 7 to give the red color development to the said latent image. After this, a black toner charged in the positive polarity is supplied from the 2nd developing device 8 to carry out the black color development. A uni-component black insulating magnetic toner 19 is stored in the device 8 to be used. The polarity is all made negative by a control charger 9 and then transcribed onto the transfer paper 14. The externalvibrating electric fields of different frequencies are applied to the 1st and 2nd development rollers respectively, otherwise the DC voltages are superposed. |
