Full-color electrophotographic apparatus using liquid toner containing resin

A full-color electrophotographic apparatus to form a full color image on a printing medium using a nonvolatile, high-viscosity, high-concentration liquid toner, comprising:

• an intermediate transfer member on which color toner images in a plurality of colors are sequentially superimposed so as to form the full-color image, and the full-color image being heat-melt-transferred to the printing medium;
• a photoconductor member to form the color toner images, the intermediate transfer member being maintained at a temperature equal to or higher than a softening start temperature of resin contained in the liquid toner and equal to or lower than a withstand temperature of the photoconductor member;
• a carrier-removing mechanism provided on the intermediate transfer member so as to remove a carrier when each of the color toner images is transferred to the intermediate transfer member, said carrier-removing mechanism comprising a carrier-removing roller to which a bias having a same polarity as that of particles of the toner on the intermediate transfer member and in rotary contact with the toner images on the intermediate transfer member so as to remove the carrier while packing the toner softened by a force of an electric field induced by the bias;
• a transfer section, comprising a backup roller, to press against the printing medium the toner images which have been formed on the intermediate transfer member and from which the carrier has been removed, to thereby transfer the toner images to the printing medium;
• and
• a fixation section for fixing the transferred toner image,
• wherein a mixture of two types of resins of different softening temperatures is used as resin contained in the nonvolatile, high-viscosity, high-concentration liquid toner;
• and
• when Tg1 represents a softening temperature of one resin, Tg2 represents a softening temperature of the other resin, Tg3 represents a softening temperature of the mixed resin, Tm3 represents a melting temperature of the mixed resin, and T4 represents a temperature of the image bearing member,
• the two types of resins are selected so as to establish the relation Tg1<Tg3<Tg2<Tm3, and means for controlling a temperature of the intermediate transfer member is provided so as to establish the relation Tg1<T4<Tg2<Tm3.

A full-color electrophotographic apparatus to form a full color image on a printing medium using a nonvolatile, high-viscosity, high-concentration liquid toner, comprising:

• an intermediate transfer member on which color toner images in a plurality of colors are sequentially superimposed so as to form the full-color image, and the full-color image being heat-melt-transferred to the printing medium;
• a photoconductor member to form the color toner images, the intermediate transfer member being maintained at a temperature equal to or higher than a softening start temperature of resin contained in the liquid toner and equal to or lower than a withstand temperature of the photoconductor member;
• a carrier-removing mechanism provided on the intermediate transfer member so as to remove a carrier when each of the color toner images is transferred to the intermediate transfer member, said carrier-removing mechanism comprising a carrier-removing roller to which a bias having a same polarity as that of particles of the toner on the intermediate transfer member and in rotary contact with the toner images on the intermediate transfer member so as to remove the carrier while packing the toner softened by a force of an electric field induced by the bias;
• a transfer section, comprising a backup roller, to press against the printing medium the toner images which have been formed on the intermediate transfer member and from which the carrier has been removed, to thereby transfer the toner images to the printing medium;
• a fixation section for fixing the transferred toner image, the fixation section being separate from the transfer section, wherein the fixation section comprises a first fixation section and a second fixation section;
• the first fixation section and the second fixation section are configured in such a manner as not to be drivingly linked to an image formation section including the intermediate transfer member, the photoconductor member, and a development section;
• and
• the first fixation section is configured in such a manner as to apply a sufficient pressure for enhancing toner cohesion to the printing medium which is insufficient at the time of transfer, so as to ensure fixation strength, while being heated to a temperature higher than the melting point of the toner solids;
• and the second fixation section is configured in such a manner as to apply pressure lower than the pressure which the first fixation section applies.

A full-color electrophotographic apparatus to form a full color image on a printing medium using a nonvolatile, high-viscosity, high-concentration liquid toner, comprising:

• an intermediate transfer member on which color toner images in a plurality of colors are sequentially superimposed so as to form the full-color image, and the full-color image being heat-melt-transferred to the printing medium;
• a photoconductor member to form the color toner images, the intermediate transfer member being maintained at a temperature equal to or higher than a softening start temperature of resin contained in the liquid toner and equal to or lower than a withstand temperature of the photoconductor member;
• a carrier-removing mechanism provided on the intermediate transfer member so as to remove a carrier when each of the color toner images is transferred to the intermediate transfer member, said carrier-removing mechanism comprising a carrier-removing roller to which a bias having a same polarity as that of particles of the toner on the intermediate transfer member and in rotary contact with the toner images on the intermediate transfer member so as to remove the carrier while packing the toner softened by a force of an electric field induced by the bias;
• a transfer section, comprising a backup roller, to press against the printing medium the toner images which have been formed on the intermediate transfer member and from which the carrier has been removed, to thereby transfer the toner images to the printing medium;
• and
• a fixation section for fixing the transferred toner image,
• wherein the fixation section comprises:
• heating means for heating the printing medium to which toner has been transferred, so as to melt a resin component of toner particles;
• and
• press fixation means for fixing the toner image through causing the printing medium to pass through a fixation nip zone where pressure is applied to a resin component of toner particles molten on the printing medium, and at least a toner image side of the printing medium is heat-retained,
• wherein the printing medium receives heat from the heating means and the pressure from the press fixation means at different times.

An apparatus to form a color image on a printing medium using a liquid toner containing a resin, comprising:

• a transfer member to receive the color image thereon;
• a transfer unit to transfer the color image from the transfer member to the printing medium;
• a temperature setting unit to set a temperature (T1) of the printing medium as measured in the transfer unit to be greater than a softening temperature (Tg) of the resin contained in the toner and lower than a melting temperature (Tm) of the resin;
• a preheating unit to preheat the printing medium to a temperature required for transfer of the color image before the printing medium is received by the transfer unit;
• and
• a temperature control to control a temperature (T2) of the transfer member such that the temperature (T2) is greater than the softening temperature (Tg) and lower than the temperature (T1).

An apparatus to form a color image on a printing medium, comprising:

• a transfer member to receive a liquid toner containing a mixed resin to thereby form the color image thereon;
• a transfer unit to transfer the color image from the transfer member to the printing medium;
• and
• a temperature controller to control a temperature T4 of the transfer member,
• the mixed resin comprising a first resin having a softening temperature Tg1 and a second resin having a softening temperature Tg2 different from Tg1, so that Tg1<Tg3<Tg2<Tm3 is satisfied, wherein Tg3 represents a softening temperature of the mixed resin and Tm3 represents a melting temperature of the mixed resin, and the temperature controller controls the temperature T4 so that Tg1<T4<Tg2<Tm3 is satisfied.

An apparatus to form a color image on a printing medium using a liquid toner containing a resin, comprising:

• a photoconductor member to form a plurality of images of different colors thereon;
• a transfer member to receive the plurality of images to thereby form the color image thereon;
• a transfer unit to transfer the color image from the transfer member to the printing medium;
• and
• a fixation unit to fix the transferred color image, comprising:
• a first section to apply a first pressure to the printing medium to thereby fix the color image to the printing medium, and
• a second section to apply a second pressure to the printing medium which is lower than the first pressure,
• the first and second sections not being drivingly linked to the transfer member or the photoconductor member.