Image forming apparatus and ejection state determination method

1. An image forming apparatus, comprising:

an ink ejection device which ejects ink through nozzles, the ink containing coloring material;

a treatment liquid ejection device which ejects treatment liquid through nozzles, the treatment liquid being a colorless transparent liquid containing no coloring material, the treatment liquid containing infrared-absorbing material and having at least one of an action of insolubilizing the coloring material in the ink when contacting with the ink, an action of aggregating the coloring material in the ink when contacting with the ink, and an action of preventing dispersion of the coloring material in the ink when contacting with the ink;

a test pattern formation control device which controls the treatment liquid ejection device to eject the treatment liquid to form a prescribed test pattern onto one of a recording medium and an intermediate transfer body by depositing the treatment liquid, the prescribed test pattern being formed with only the treatment liquid on which the ink is not superimposed;

an infrared irradiating device which irradiates infrared light onto the treatment liquid having been ejected from the treatment liquid ejection device;

a treatment liquid determination device which includes a photoelectric transducer having sensitivity to the infrared light and determining a formation state of the prescribed test pattern formed with only the treatment liquid on which the ink is not superimposed; and

a treatment liquid ejection defect judgment device which judges a number and positions of defective ones of the nozzles of the treatment liquid ejection device according to a determination signal obtained from the photoelectric transducer of the treatment liquid determination device; and

an image processing device which specifies a deposition arrangement of the ink in such a manner that usage rate for the nozzle of the ink ejection device corresponding to the position of the defective nozzle of the treatment liquid ejection device is reduced.

2. An image forming apparatus, comprising:

an ink ejection device which ejects ink through nozzles, the ink containing coloring material;

a treatment liquid ejection device which ejects treatment liquid through nozzles, the treatment liquid being a colorless transparent liquid containing no coloring material, the treatment liquid containing infrared-absorbing material and having at least one of an action of insolubilizing the coloring material in the ink when contacting with the ink, an action of aggregating the coloring material in the ink when contacting with the ink, and an action of preventing dispersion of the coloring material in the ink when contacting with the ink;

a test pattern formation control device which controls the treatment liquid ejection device to eject the treatment liquid to form a prescribed test pattern onto one of a recording medium and an intermediate transfer body by depositing the treatment liquid, the prescribed test pattern being formed with only the treatment liquid on which the ink is not superimposed;

an infrared irradiating device which irradiates infrared light onto the treatment liquid having been ejected from the treatment liquid ejection device;

a treatment liquid determination device which includes a photoelectric transducer having sensitivity to the infrared light and determining a formation state of the prescribed test pattern formed with only the treatment liquid on which the ink is not superimposed; and

a treatment liquid ejection defect judgment device which judges a number and positions of defective ones of the nozzles of the treatment liquid ejection device according to a determination signal obtained from the photoelectric transducer of the treatment liquid determination device; and

a first restoration control device which performs control for carrying out a maintenance operation for restoring ejection performance of the treatment liquid ejection device when the number of the defective nozzles of the treatment liquid ejection device exceeds a first threshold value.

3. The image forming apparatus as defined in claim 2 , further comprising:

a recording medium type identification device which identifies a type of the recording medium; and

a threshold value setting device which sets the first threshold value according to the type of the recording medium.

4. The image forming apparatus as defined in claim 2 , further comprising:

an ink determination device which includes a photoelectric transducer having sensitivity to visible light;

an ink ejection defect judgment device which judges a number and positions of defective ones of the nozzles of the ink ejection device according to a determination signal obtained from the photoelectric transducer of the ink determination device; and

a second restoration control device which performs control for carrying out a maintenance operation for restoring ejection performance of the ink ejection device when the number of the defective nozzles of the ink ejection device exceeds a second threshold value smaller than the first threshold value.

5. The image forming apparatus as defined in claim 4 , further comprising:

a recording medium type identification device which identifies a type of the recording medium; and

a threshold value setting device which sets the first threshold value and the second threshold value according to the type of the recording medium.