Inkjet recording apparatus and recording method by the same

1. An inkjet recording apparatus comprising:

an inkjet head that ejects ink on a printing medium;

a conveyance motor causing conveyance of the printing medium;

a discharge motor causing discharge of the printing medium;

a printing medium surface sensor, located at an upper-stream side of the inkjet head apart from the inkjet head in a printing medium conveyance direction, that senses a foreign substance representing an image printed color material that includes a resin and that is different from an ink adhered on the printing medium beforehand; and

a controller that drives the discharge motor to discharge a printing medium without ejecting ink from the inkjet head if an after-printing mode in which printing is made on the printing medium on which the image is printed beforehand is not set if the foreign substance color material that includes the resin and that is different from the ink is detected on the printing medium through the printing medium surface sensor, or drives the discharge motor to discharge a printing medium after ejecting ink on the printing medium from the inkjet head if the after-printing mode is set if the foreign substance color material that includes the resin and that is different from the ink is detected on the printing medium through the printing medium surface sensor.

2. The inkjet recording apparatus according to claim 1 ,

further comprising a medium cassette that stores a plurality of the printing mediums, a length of the printing medium stored in the cassette in the printing medium conveyance direction being shorter than a distance between the printing medium surface sensor and the inkjet head.

3. The inkjet recording apparatus according to claim 1 ,

wherein the recording medium surface sensor senses only an area on the printing medium where ink is ejected by the inkjet head if the after-printing mode is set.

4. The inkjet recording apparatus according to claim 1 ,

wherein the controller validates the after-printing mode if printing is performed only on a fixed form of the printing medium on which the image of the fixed form is printed beforehand.

5. The inkjet recording apparatus according to claim 1 ,

wherein the controller validates the after-printing mode if only a text data is printed on the printing medium on which the image is printed beforehand.

6. The inkjet recording apparatus according to claim 1 ,

wherein the controller directs issuance of a warning information if the controller detects the foreign substance color material that includes the resin and that is different from the ink on the printing medium through the printing medium surface sensor if the after-printing mode is not set.

7. The inkjet recording apparatus according to claim 6 ,

further comprising a display that displays the warning information.

8. The inkjet recording apparatus according to claim 1 ,

wherein the controller directs issuance of a warning information if the controller detects the foreign substance color material that includes the resin and that is different from the ink in an after-printing area on the printing medium through the printing medium surface sensor if the after-printing mode is set.

9. The inkjet recording apparatus according to claim 1 ,

wherein the controller detects both surfaces of a single printing medium through the printing medium surface sensor if the after-printing mode is set.

10. The inkjet recording apparatus according to claim 9 ,

further comprising a medium guide pair that guides the printing medium conveyed,

wherein the printing medium surface sensor includes a pair of printing medium surface sensors which is disposed at the opposite sides of the medium guide pair, respectively.

11. The inkjet recording apparatus according to claim 9 ,

wherein the controller directs the discharge motor to discharge the printing medium without determining the state of the second surface if the controller determines that the foreign substance color material that includes the resin and that is different from the ink is present on the first surface of the printing medium.

12. The inkjet recording apparatus according to claim 1 ,

wherein the controller directs the inkjet head to perform printing if the after-printing mode is set after the controller determines that the foreign substance color material that includes the resin and that is different from the ink is not present on a first and second surfaces of the printing medium.

13. The inkjet recording apparatus according to claim 12 ,

further comprising a medium cassette that stores a plurality of printing mediums, a length of the printing medium stored in the cassette in the printing medium conveyance direction being shorter than a distance between the printing medium surface sensor and the inkjet head.

14. The inkjet recording apparatus according to claim 1 ,

further comprising an interface that receives data from an external apparatus.

15. The inkjet recording apparatus according to claim 1 ,

wherein the foreign substance resin is a transparent resin.

16. A method of printing by an inkjet recording apparatus comprising: conveying a printing medium by a conveyance motor;

judging whether a foreign substance representing an image is present color material that includes a resin and that is different from an ink adhered on the surface of the printing medium;

discharging the printing medium by a discharge motor without ejecting ink on the printing medium by an inkjet head, if an after-printing mode in which printing is made on the printing medium on which the image is printed beforehand is not set if the foreign substance color material that includes the resin and that is different from the ink representing the image is detected on the surface of the printing medium; and

discharging the printing medium by the discharge motor after ejecting ink on the printing medium by the inkjet head, if the after-printing mode is set.

17. The method of printing by the inkjet recording apparatus according to claim 16 ,

further comprising issuing a warning information if the controller detects the foreign substance color material that includes the resin and that is different from the ink in an after-printing area on the printing medium if the after-printing mode is set.

18. The method of printing by the inkjet recording apparatus according to claim 16 ,

wherein the foreign substance resin is a transparent resin.

19. The inkjet recording apparatus according to claim 1,

wherein the printing medium surface sensor distinguishes whether the color material that includes the resin and that is different from the ink comprises black toner or color toner.

20. The inkjet recording apparatus according to claim 1,

wherein the printing medium surface sensor is positioned so that the printing medium surface sensor senses an entire length of the printing medium for a color material that includes the resin and that is different from the ink before the printing medium is conveyed adjacent the inkjet head.