Transfer humidity control device
AssigneeRank Xerox Ltd.
InventorToshio Watanabe
Life of this patent
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Abstract
In an electrostatographic copying system wherein an image on an initial image support is transferred to a copy sheet, particularly by a transfer corona generator assisted by an auxiliary transfer corona generator applying pre-transfer charges to the initial image support, opposing conductive rollers measure the conductivity of each copy sheet prior to transfer and through a control circuit vary the voltages applied to both the transfer corona generator and the auxiliary transfer corona generator means accordingly. A relay switching system is disclosed automatically selecting between AC and two levels of DC transfer voltages in response to four different copy sheet humidity conditions to optimize the image transfer.
Claims13
In an electrostatographic copying system wherein an image on an initial image support is transferred to a second image support by variable transfer means, which transfer is affected by variations in the conductivity of the second image support, wherein said transfer means includes a transfer corona generator means to which a first voltage is applied for applying transfer charges to said second image support, and wherein said transfer means includes an auxiliary transfer corona generator means to which a second voltage is applied for applying pre-transfer charges to said initial image support, the improvement comprising:
- conductivity sensing means for sensing the conductivity of the second image support prior to said transfer;
- and transfer control circuit means controlled by said conductivity sensing means for varying both said first and second voltages applied to said transfer corona generator means and to said auxiliary transfer corona generator means in response to variations in the conductivity of the second image support sensed by said conductivity sensing means.
In an electrostatographic copying method wherein an image on an initial image support is transferred to a second image support by variable electrostatic transfer means, which transfer is affected by variations in the conductivity of the second image support, wherein said transfer means includes a transfer corona generator means to which first voltage is applied for applying transfer charges to said second image support, and wherein said transfer means further includes an auxiliary transfer corona generator means to which a second voltage is applied for applying pre-transfer charges to said initial image support, the improvement comprising:
- sensing the conductivity of the second image support prior to said transfer;
- and
- varying both said first and second voltages applied to said transfer corona generator means and said auxiliary transfer corona generator means in response to variations in the conductivity of the second image support sensed by said conductivity sensing means to compensate for variations in the second image support.
Dependencies are inferred from the claim text.