Image forming apparatus

An image forming apparatus comprising:

• a toner supply unit;
• an image forming element formed in the shape of a cylinder to which toner is adsorbed from the toner supply unit;
• an image developing unit comprising a control unit including a substrate disposed outside of the image forming element, a plurality of electrodes disposed on an edge portion of the substrate to be separated in the direction of length of the image forming element and disposed adjacent to an outer circumferential surface of the image forming element, and a plurality of control chips installed on the substrate to individually apply a voltage to each of the electrodes and, wherein said control unit selectively separates from the image forming element at least a part of the toner adsorbed to the image forming element;
• and
• a toner return unit which returns the toner separated from the image forming element by the image developing unit, to the toner supply unit.

An image forming apparatus comprising:

• a toner supply unit;
• an image forming element formed in the shape of a cylinder to which toner is adsorbed from the toner supply unit;
• an image developing unit which selectively separates from the image forming element at least a part of the toner adsorbed to the image forming element, said image developing unit comprising:
• a first control unit including a first substrate disposed on an outer side of the image forming element, a plurality of first electrodes disposed on an edge portion of the first substrate to be disposed adjacent to an outer circumferential surface of the image forming element, and a plurality of first control chips installed on the first substrate to individually apply a voltage to each of the plurality of the first electrodes;
• and
• a second control unit including a second substrate epitaxially deposited in a direction of thickness of the first substrate, a plurality of second electrodes disposed on an edge portion of the second substrate to be separated to alternate with each of the plurality of the first electrodes in a lengthwise direction of the image forming element and to be disposed adjacent to the outer circumferential surface of the image forming element, and a plurality of second control chips installed on the second substrate to individually apply a voltage to each of the plurality of the second electrodes;
• and
• a toner return unit which returns the toner separated from the image forming element by the image developing unit, to the toner supply unit.

An image forming apparatus comprising:

• a toner supply unit;
• an image forming element formed in the shape of a cylinder to which toner is adsorbed from the toner supply unit;
• an image developing unit which selectively separates from the image forming element at least a part of the toner adsorbed to the image forming element, said image developing unit comprising:
• a first control unit including a first substrate disposed on an outer side of the image forming element, a plurality of first electrodes disposed on an edge portion of the first substrate to be disposed adjacent to an outer circumferential surface of the image forming element, and a plurality of first control chips installed on the first substrate to apply an equal voltage to the plurality of the first electrodes;
• and
• a second control unit including a second substrate epitaxially deposited in a direction of thickness of the first substrate, a plurality of second electrodes disposed on an edge portion of the second substrate to be separated to alternate with each of the plurality of the first electrodes in a lengthwise direction of the image forming element and to be disposed adjacent to the outer circumferential surface of the image forming element, and a plurality of second control chips installed on the second substrate to individually apply a voltage to each of the plurality of the second electrodes;
• and
• a toner return unit which returns the toner separated from the image forming element by the image developing unit, to the toner supply unit.

An image forming apparatus comprising:

• a toner supply unit;
• an image forming element formed in the shape of a cylinder to which toner is adsorbed from the toner supply unit;
• an image developing unit comprising a control unit including a substrate disposed on an outer side of the image forming element, a plurality of electrodes disposed on an edge portion of the substrate to be separated in the lengthwise direction of the image forming element and disposed adjacent to an outer circumferential surface of the image forming element, and a plurality of control chips installed on the substrate to individually apply voltage to each of the electrodes, wherein said control unit selectively separates from the image forming element at least a part of the toner adsorbed to the image forming elements;
• a magnet formed to have a magnetic force smaller than a magnetic force that adsorbs the toner to the image forming element and disposed in the lengthwise direction of the image forming element and in a direction of thickness of the substrate;
• and
• a magnetic insulating unit disposed longitudinally in relation to the image forming element and in a same line with each of the electrodes in a direction of thickness of a magnetic force generation surface of the magnet with respect to the image forming element;
• and a toner return unit which returns the toner separated from the image forming element by the image developing unit, to the toner supply unit.