Image forming apparatus and method

1. An image forming apparatus, comprising:

an ejection head which ejects ink having electrorheological properties toward a recording medium;

an electric field application device which applies an electric field to droplets of the ink deposited on a surface of the recording medium;

an electric field intensity control device which controls intensity of the electric field in such a manner that the ink in the droplets has a prescribed viscosity; and

a fixing promotion device which carries out processing for promoting fixing of the ink on the recording medium, in a state where the electric field is applied by the electric field application device.

2. The image forming apparatus as defined in claim 1 , further comprising:

a medium information acquiring device which acquires information relating to a state of the recording medium,

wherein the electric field intensity control device controls the electric field intensity according to the information acquired by the medium information acquiring device.

3. The image forming apparatus as defined in claim 2 , wherein the medium information acquiring device comprises a surface potential determining device which determines an electric potential at the surface of the recording medium.

4. The image forming apparatus as defined in claim 2 , wherein the medium information acquiring device comprises a recording medium type determining device which determines a type of the recording medium.

5. The image forming apparatus as defined in claim 1 , wherein:

the ink is a radiation-curable ink; and

the fixing promotion device comprises a radiation irradiating device which irradiates radiation that causes the ink to harden.

6. The image forming apparatus as defined of claim 1 , further comprising:

an electrostatic attraction device which holds the recording medium by means of electrostatic attraction,

wherein the electrostatic attraction device functions as the electric field application device.

7. The image forming apparatus as defined in claim 1 , further comprising an earthed electrode member which is arranged on at least an ejection surface side of the ejection head.

8. The image forming apparatus as defined in claim 1 , further comprising a static-elimination device which removes electrical charge from the recording medium after processing by the fixing promotion device.

9. An image forming method, comprising:

an ink ejection step of ejecting ink having electrorheological properties toward a recording medium from an ejection head;

an electric field application step of applying an electric field to droplets of the ink deposited on a surface of the recording medium;

an electric field intensity control step of controlling intensity of the electric field in such a manner that the ink in the droplets has a prescribed viscosity; and

a fixing promotion step of carrying out processing for promoting fixing of the ink on the recording medium, in a state where the electric field is applied in the electric field application step.

10. The image forming apparatus of claim 1 , wherein the electric field application device applies the electric field based on a type of medium the ink is being applied to, a type of ink stored in the ejection head, and a surface potential of the recording medium.

11. The image forming apparatus of claim 1 , wherein the electric field intensity control device controls intensity of the electric field based on the prescribed viscosity of the ink droplets on the recording medium.