Fixing device, image forming apparatus, and toner image fixing method

An image forming apparatus comprising:

• image forming device that forms toner image on a recording medium;
• and a fixing device includes:
• a plurality of laser beam irradiation units each of which includes a plurality of laser beam sources and emits a plurality of laser beams, generated by the plurality of laser beam sources, to a surface of the recording medium, and
• a conveying unit that conveys the recording medium and/or the plurality of laser beam irradiation unit such that regions on the recording medium irradiated with the plurality of laser beams are moved relative to the conveyed recording medium in a conveying direction,
• wherein adjacent two of the plurality of laser beam irradiation units are disposed with a gap therebetween in the conveying direction of the recording medium and the plurality of laser beams emitted from one of the laser beam irradiation units is spatially independent from the plurality of laser beams emitted from the other of the laser beam irradiation units,
• wherein when the plurality of laser beams is emitted to the toner image so as to fix the toner image to the recording medium, the plurality of laser beams satisfies following conditions:
• (A) the plurality of laser beams has substantially the same beam power and substantially the same width in the conveying direction in the irradiated regions,
• (B) the plurality of laser beams is independently emitted to the toner image, and
• (C) when the toner image includes a plurality of toner layers, toner temperature of interfacial portions between the toner image and the surface of the recording medium reaches toner fixing temperature in the irradiation except for the irradiation of a first laser beam among the plurality of laser beams, and
• wherein each of the plurality of laser beam irradiation units includes a plurality of laser beam generating elements lined up along a direction crossing the conveying direction.

A method for fixing a toner image to a recording medium, the method comprising:

• generating the toner image on the recording medium;
• irradiating the toner image with a first laser beam generated by a first laser beam unit while moving the recording medium in a conveying direction relative to the first laser beam unit;
• and
• irradiating the toner image with one or more second laser beams generated by at least one of second laser beam units,
• wherein the first laser beam irradiation unit and said at least one second laser beam unit are disposed with a gap therebetween in the conveying direction of the recording medium and the first laser beam emitted from the first laser beam unit is spatially independent from the one or more second laser beams emitted from the second laser beam unit,
• wherein the first laser beam and the one or more second laser beams satisfy the following conditions:
• (A) the first and second laser beams have substantially the same beam power and substantially the same width in the conveying direction in the irradiated regions,
• (B) the first and second laser beams are independently emitted to the toner image, and
• (C) when the toner image includes a plurality of toner layers, toner temperature of interfacial portions between the toner image and the surface of the recording medium is lower than toner fixing temperature during a period from the irradiation with the first laser beam to the irradiation with the second laser beams and reaches the toner fixing temperature by the irradiation with any one of the second laser beams, and
• wherein each of the first and second laser beam irradiation units includes a plurality of laser beam generating elements lined up along a direction crossing the conveying direction.