Color electro-photographic printing apparatus

A small-size color electro-photographic apparatus comprising:

• a photosensitive belt;
• an exposing unit for forming an electrostatic latent image by exposing said photosensitive belt;
• a plurality of developing units for different color toners;
• an intermediate transfer drum for successively superposing a toner image of a different color on said photosensitive belt to produce a color toner image;
• a transfer unit for transferring said color toner image superposed on said intermediate transfer drum to a printing medium;
• and
• a fixing unit for fixing the color toner image transferred onto the printing medium;
• wherein an outer peripheral length of said photosensitive belt is nearly equal to and not longer than an outer peripheral length of said intermediate transfer drum, said photosensitive belt being stretched in a vertical direction parallel to the direction of gravity, the developing units for different colors being vertically stacked on one side of the photosensitive belt and said intermediate transfer drum being arranged on another side of the photosensitive belt;
• wherein a diameter of said intermediate transfer drum is 70 to 150 mm.

A small-size color electro-photographic apparatus having a photosensitive belt, an exposing unit for forming an electrostatic latent image by exposing said photosensitive belt, a plurality of developing units for different colors, an intermediate transfer drum for successively superposing a toner image of a different color on said photosensitive belt to produce a color toner image, a transfer unit for transferring said color image superposed on said intermediate transfer drum to a printing medium, a fixing unit for fixing the color image transferred onto the printing medium, and a case containing a controller for controlling each of the units, wherein:

• an outer peripheral length of said photosensitive belt is nearly equal to and not longer than an outer peripheral length of said intermediate transfer drum;
• said photosensitive belt is stretched in a vertical direction parallel to the direction of gravity;
• the developing units for different colors are vertically stacked on one side of the photosensitive belt and said intermediate transfer drum is arranged on another side of the photosensitive belt;
• said photosensitive belt and the developing units arranged on one side of the photosensitive belt are formed in a unit;
• each of the developing units in said unit being linked to a cam mechanism for changing a contact gap between the developing unit and the photosensitive belt for each of the developing units so that each of the developing units contacts or approaches the photosensitive belt one-by-one according to a control signal from said controller when the developing units in said unit are mounted in said case.

A small-size color electro-photographic apparatus having a photosensitive belt, an exposing unit for forming an electrostatic latent image by exposing said photosensitive belt, a plurality of developing units for different colors, an intermediate transfer drum for successively superposing a toner image of a different color on said photosensitive belt to produce a color toner image, a transfer unit for transferring said color image superposed on said intermediate transfer drum to a printing medium, a fixing unit for fixing the color image transferred onto the printing medium, and a case containing a controller for controlling each of the units, wherein:

• the photosensitive belt is generally vertically oriented and the developing units are arranged on one side of the photosensitive belt and are formed in a unit;
• each of the developing units in said unit being provided with a cam mechanism for changing a contact gap between the developing unit and the photosensitive belt;
• at least one of the developing units disposed at respective ends of the belts is arranged at such a position that a center of a developing roll provided in the developing unit coincides with a center of a roller over which the photosensitive belt passes;
• and
• guide members for stably holding a position of the photosensitive belt are provided in an inner side of a surface of the photosensitive belt facing the developing units arranged intermediate the developing units disposed at the respective ends of the belt.

A small-size color electro-photographic apparatus having a photosensitive belt which is vertically oriented;

• a plurality of developing units stacked beside one side surface of said photosensitive belt;
• a fixing unit placed under said plurality of developing units;
• a paper cassette placed under said fixing unit;
• an intermediate transfer drum placed in a lower side portion adjacent the other side surface of said photosensitive belt;
• a photosensitive belt cleaner having an erase lamp mounted in a cabinet, a charging unit and an exposing unit placed in this order above said intermediate transfer drum;
• a transfer roller placed under said intermediate transfer drum;
• and a paper transporting path on which a sheet of paper is transported from said transfer roller to the fixing unit.

A small-sized color electro-photographic apparatus comprising:

• a loop-shaped photosensitive belt which is vertically stretched;
• a plurality of developing units stacked on one side of said photosensitive belt;
• an intermediate transfer drum placed on another side of said photosensitive belt;
• a fixing unit placed above said intermediate transfer drum;
• an exposing unit placed under said developing units;
• and
• a paper cassette placed under said photosensitive belt and exposing unit.