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(11) | EP 0 294 824 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Image forming method and apparatus therefor |
| (57) An image forming method of the present invention comprises: a first toner image formation
process for forming a first toner image by forming, on a latent image carrier, a first
latent image which corresponds to a first image and developing the first latent image
by a first toner charged to one polarity through a development selected from normal
and reverse developments so as to correspond to the polarity of the first toner; a
second toner image formation process for forming a second toner image by forming,
on the latent image carrier, a second latent image which corresponds to a second image
and developing the second latent image by a second toner charged to the other polarity
by the other development while applying a developing bias; and a transfer treatment
process for simultaneously transferring said first and second toner images to a transfer
medium; wherein said developing bias VB2 satisfies the following equations: |VT1 - VB2| > |VH2 - VB2| (1) |VT1 - VB2| > |VT1 - VH2| (2) where a surface potential of said first toner image is VT1, a background potential in said second toner image forming process is VH2, and the developing bias in said second toner image forming process is VB2. |