Image forming apparatus

An image forming apparatus comprising:

• a first group of a plurality of print heads each containing ink of a different color;
• and
• a second group of a plurality of print heads each containing ink of a different color;
• wherein each type of ink contained in said second group of print heads being different in permeability to a recording sheet from each type of ink contained in said first group of print heads;
• and
• wherein each type of ink contained in said first group of print heads being complementary color ink to ink contained in said second group of print heads.

An image forming apparatus comprising:

• a first group of a plurality of print heads each containing ink of a different color;
• and
• a second group of a plurality of print heads each containing ink of a different color;
• wherein each type of ink contained in said second group of print heads is different in permeability to a recording sheet from each type of ink contained in said first group of print heads, wherein each type of ink contained in said first group of print heads is the same in color as and lower in tone than each type of ink contained in said second group of print heads, and wherein ΔD, which is a difference between a maximum optical density ODmax and a minimum optical density ODmin, is not more than 0.1 when printing is performed by ink contained in said first group of print heads and ink contained in said second group of print heads.

An image forming apparatus comprising:

• a first group of print heads which contain toning materials of primary colors for printing, respectively;
• a second group of print heads which contain toning materials, respectively, each of the toning materials of said second group of print heads being different in color than any one of the toning materials of said first group of print heads;
• and
• a controller which controls said first and second groups of print heads, said controller being adapted to control said second group of print heads to print at a plurality of tone levels and being adapted to control each print head of said first group of print heads to respectively print at only a single tone level.

An image forming apparatus comprising:

• a first print head using a first chromatic toning material for printing dots on a recording medium;
• a second print head using a second chromatic toning material for printing dots on said recording medium, said second chromatic toning material being different in tone from said first chromatic toning material, one of the first and second print heads being adapted to print ink dots of a plurality of sizes and the other of the first and second print heads being adapted to print ink dots of only a single size;
• and
• a controller for controlling said first and second print heads to print dots so as to form an image on said recording medium, said image comprising a plurality of pixels,
• wherein said controller is adapted to control a tone of each pixel by controlling therefor:
• (a) the diameter of dot by using said one of the first and second print heads and (b) the toning material used to print the dot by selecting one of said first and second print heads.

An image forming apparatus comprising:

• a first group of a plurality of print heads each containing ink of a different color;
• and
• a second group of a plurality of print heads each containing ink of a different color;
• wherein each type of ink contained in said second group of print heads is different in permeability to a recording sheet from each type of ink contained in said first group of print heads, and wherein each of the plurality of print heads of one of the first group and the second group is capable of changing a size of dots printed.

An inkjet printer comprising:

• a cyan inkjet head group comprising first cyan inkjet nozzles and second cyan inkjet nozzles, said first cyan inkjet nozzles being for ejecting ink drops of a first cyan color ink, said second cyan inkjet nozzles being for ejecting ink drops of a second cyan color ink which is lighter than said first cyan color ink;
• a magenta inkjet head group comprising first magenta inkjet nozzles and second magenta inkjet nozzles, said first magenta inkjet nozzles being for ejecting ink drops of a first magenta color ink, said second magenta inkjet nozzles being for ejecting ink drops of a second magenta color ink which is lighter than said first magenta color ink;
• a yellow inkjet head group consisting of a plurality of yellow inkjet nozzles, said yellow inkjet nozzles being for ejecting ink drops of a single yellow color ink;
• and
• a black inkjet head group comprising a plurality of black inkjet nozzles, said black inkjet nozzles being for ejecting ink drops of a single black color ink, said black inkjet nozzles being arranged such that a pitch of drops ejected therefrom is smaller than a pitch of drops ejected from any one of said first cyan inkjet nozzles, said second cyan inkjet nozzles, said first magenta inkjet nozzles, said second magenta inkjet nozzles and said yellow inkjet nozzles.