Image forming apparatus

Abstract

The image forming apparatus includes: a recording head which has a plurality of recording elements; an intermediate transfer medium on which an image is recorded temporarily by the recording head while the intermediate transfer medium implements relative movement with respect to the recording head; an image defect determination device which is disposed on a downstream side of the recording head in terms of a direction of the relative movement of the intermediate transfer medium and which determines whether the image recorded on the intermediate transfer medium includes an image defect or not; a transfer device which is disposed on a downstream side of the image defect determination device in terms of the direction of the relative movement of the intermediate transfer medium and which transfers the image recorded on the intermediate transfer medium, to a recording medium; and an image correction device which creates correction data according to information about the image defect if the image defect determination device determines that the image recorded on the intermediate transfer medium includes the image defect, wherein, if the image defect determination device determines that the image recorded on the intermediate transfer medium includes the image defect, an image based on the correction data is recorded on the intermediate transfer medium by the recording head.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The nature of this invention, as well as other objects and advantages thereof, will be explained in the following with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures and wherein:

FIG. 1 is a general schematic view showing an inkjet recording apparatus which forms an image recording apparatus according to a first embodiment of the present invention;

FIG. 2 is a flowchart showing an image correction according to the first embodiment;

FIG. 3A is a plan view perspective diagram showing a structural embodiment of a print head of an image forming apparatus according to an embodiment of the present invention, and FIG. 3B is a principal enlarged view of the print head;

FIG. 4 is a plan view perspective diagram showing another structural embodiment of a full line type of head;

FIG. 5 is a cross-sectional view along line 5-5 in FIGS. 3A and 3B;

FIG. 6 is an enlarged view showing a nozzle arrangement in the print head shown in FIG. 3A;

FIG. 7 is a principal block diagram showing the system configuration of an inkjet recording apparatus according to an embodiment of the present invention;

FIG. 8 is a general schematic view showing an inkjet recording apparatus which forms an image recording apparatus according to second, third and fifth embodiments of the present invention;

FIG. 9 is a flowchart showing an image correction according to the second embodiment;

FIG. 10 is a flowchart showing an image correction according to the third embodiment;

FIG. 11 is a general schematic view showing an inkjet recording apparatus which forms an image recording apparatus according to a fourth embodiment of the present invention;

FIG. 12 is a flowchart showing an image correction according to the fifth embodiment;

FIG. 13 is an illustrative diagram showing an embodiment of a density profile before correction of density non-uniformity according to an embodiment of the present invention;

FIG. 14 is an illustrative diagram showing a state after correction of density non-uniformity according to an embodiment of the present invention;

FIG. 15 is a diagram illustrating the relationship between a density profile of an actual print model and a density profile of a δ function type of print model;

FIG. 16 is a graph of a power spectrum showing the results of correction according to an embodiment of the present invention;

FIG. 17 is a graph illustrating the relationship between the number of nozzles (N) used for correction and the density correction coefficients;

FIG. 18 is a flowchart showing a sequence of image processing according to an embodiment of the present invention;

FIG. 19 is a conceptual diagram of density non-uniformity correction processing according to an embodiment of the present invention; and

FIG. 20 is a flowchart showing a sequence of processing for updating the correction data.

Claims

1. An image forming apparatus comprising: a recording head which has a plurality of recording elements;an intermediate transfer medium on which an image is recorded temporarily by the recording head while the intermediate transfer medium implements relative movement with respect to the recording head;an image defect determination device which is disposed on a downstream side of the recording head in terms of a direction of the relative movement of the intermediate transfer medium and which determines whether the image recorded on the intermediate transfer medium includes an image defect or not;a transfer device which is disposed on a downstream side of the image defect determination device in terms of the direction of the relative movement of the intermediate transfer medium and which transfers the image recorded on the intermediate transfer medium, to a recording medium; andan image correction device which creates correction data according to information about the image defect if the image defect determination device determines that the image recorded on the intermediate transfer medium includes the image defect,wherein, if the image defect determination device determines that the image recorded on the intermediate transfer medium includes the image defect, an image based on the correction data is recorded on the intermediate transfer medium by the recording head.

2. The image forming apparatus as defined in claim 1, wherein the intermediate transfer medium is separated from the transfer device if the image defect determination device determines that the image recorded on the intermediate transfer medium includes the image defect.

3. The image forming apparatus as defined in claim 1, further comprising an ink cleaning device which is disposed on an upstream side of the recording head in terms of the direction of the relative movement of the intermediate transfer medium.

4. An image forming apparatus comprising: a recording head which has a plurality of recording elements;an intermediate transfer medium on which an image is recorded temporarily by the recording head while the intermediate transfer medium implements relative movement with respect to the recording head;an image defect determination device which is disposed on a downstream side of the recording head in terms of a direction of the relative movement of the intermediate transfer medium and which determines whether the image recorded on the intermediate transfer medium includes an image defect or not;an ink cleaning device which is disposed on a downstream side of the image defect determination device in terms of the direction of the relative movement of the intermediate transfer medium and which removes ink deposited on the intermediate transfer medium by the recording head;a transfer device which is disposed on a downstream side of the ink cleaning device in terms of the direction of the relative movement of the intermediate transfer medium and which transfers the image recorded on the intermediate transfer medium, to a recording medium; andan image correction device which creates correction data according to information about the image defect if the image defect determination device determines that the image recorded on the intermediate transfer medium includes the image defect,wherein, if the image defect determination device determines that the image recorded on the intermediate transfer medium includes the image defect, then the ink deposited on the intermediate transfer medium by the recording head is removed by the ink cleaning device and an image based on the correction data is recorded on the intermediate transfer medium by the recording head.

5. An image forming apparatus comprising: a recording head which has a plurality of recording elements;an intermediate transfer medium on which an image is recorded temporarily by the recording head while the intermediate transfer medium implements relative movement with respect to the recording head;an image defect determination device which is disposed on a downstream side of the recording head in terms of a direction of the relative movement of the intermediate transfer medium and which determines whether the image recorded on the intermediate transfer medium includes an image defect or not;a transfer device which is disposed on a downstream side of the image defect determination device in terms of the direction of the relative movement of the intermediate transfer medium and which transfers the image recorded on the intermediate transfer medium, to a recording medium;an ink cleaning device which is disposed on a downstream side of the transfer device and on an upstream side of the recording head in terms of the direction of the relative movement of the intermediate transfer medium and which removes ink deposited on the intermediate transfer medium by the recording head; andan image correction device which creates correction data according to information about the image defect if the image defect determination device determines that the image recorded on the intermediate transfer medium includes the image defect,wherein, if the image defect determination device determines that the image recorded on the intermediate transfer medium includes the image defect, then the transfer device is separated from the intermediate transfer medium, the ink deposited on the intermediate transfer medium by the recording head is removed by the ink cleaning device, and an image based on the correction data is recorded on the intermediate transfer medium by the recording head.

6. An image forming apparatus comprising: a recording head which has a plurality of recording elements;an intermediate transfer medium on which an image is recorded temporarily by the recording head while the intermediate transfer medium implements relative movement with respect to the recording head;an image defect determination device which is disposed on a downstream side of the recording head in terms of a direction of the relative movement of the intermediate transfer medium and which determines whether the image recorded on the intermediate transfer medium includes an image defect or not;an ink cleaning device which is disposed on a downstream side of the image defect determination device in terms of the direction of the relative movement of the intermediate transfer medium and which removes ink deposited on the intermediate transfer medium by the recording head;a transfer device which is disposed on a downstream side of the ink cleaning device in terms of the direction of the relative movement of the intermediate transfer medium and which transfers the image recorded on the intermediate transfer medium, to a recording medium; andan image correction device which creates correction data according to information about the image defect if the image defect determination device determines that the image recorded on the intermediate transfer medium includes the image defect, wherein:a test pattern image is recorded on the intermediate transfer medium by the recording head, the image defect determination device determines whether the test pattern image recorded on the intermediate transfer medium includes an image defect or not, and the ink cleaning device removes ink deposited on the intermediate transfer medium after the image defect determination device determines whether the test pattern image recorded on the intermediate transfer medium includes the image defect or not; andif the image defect determination device determines that the test pattern image recorded on the intermediate transfer medium includes the image defect, then the image correction device creates correction data according to information about the image defect included in the test pattern image and an image based on the correction data is recorded on the intermediate transfer medium by the recording head.

7. An image forming apparatus comprising: a recording head which has a plurality of recording elements;an intermediate transfer medium on which an image is recorded temporarily by the recording head while the intermediate transfer medium implements relative movement with respect to the recording head;an image defect determination device which is disposed on a downstream side of the recording head in terms of a direction of the relative movement of the intermediate transfer medium and which determines whether the image recorded on the intermediate transfer medium includes an image defect or not;a transfer device which is disposed on a downstream side of the image defect determination device in terms of the direction of the relative movement of the intermediate transfer medium and which transfers the image recorded on the intermediate transfer medium, to a recording medium;an ink cleaning device which is disposed on a downstream side of the transfer device and on an upstream side of the recording head in terms of the direction of the relative movement of the intermediate transfer medium and which removes ink deposited on the intermediate transfer medium by the recording head; andan image correction device which creates correction data according to information about the image defect if the image defect determination device determines that the image recorded on the intermediate transfer medium includes the image defect, wherein:a test pattern image is recorded on the intermediate transfer medium by the recording head, the image defect determination device determines whether the test pattern image recorded on the intermediate transfer medium includes an image defect or not, and the transfer device is separated from the intermediate transfer medium and the ink cleaning device removes ink deposited on the intermediate transfer medium after the image defect determination device determines whether the test pattern image recorded on the intermediate transfer medium includes the image defect or not; andif the image defect determination device determines that the test pattern image recorded on the intermediate transfer medium includes the image defect, then the image correction device creates correction data according to information about the image defect included in the test pattern image and an image based on the correction data is recorded on the intermediate transfer medium by the recording head.

8. The image forming apparatus as defined in claim 1, wherein maintenance of the recording head is not carried out until printing according to a print instruction information received by the image forming apparatus is completed.

9. The image forming apparatus as defined in claim 4, wherein maintenance of the recording head is not carried out until printing according to a print instruction information received by the image forming apparatus is completed.

10. The image forming apparatus as defined in claim 5, wherein maintenance of the recording head is not carried out until printing according to a print instruction information received by the image forming apparatus is completed.

11. The image forming apparatus as defined in claim 6, wherein maintenance of the recording head is not carried out until printing according to a print instruction information received by the image forming apparatus is completed.

12. The image forming apparatus as defined in claim 7, wherein maintenance of the recording head is not carried out until printing according to a print instruction information received by the image forming apparatus is completed.

13. The image forming apparatus as defined in claim 1, wherein the image correction device comprises: a correction range setting unit which selects N correction recording elements (where N is an integer which is 2 or more) used for correcting output density, from the plurality of recording elements;a correction coefficient setting unit which sets density correction coefficients for the N correction recording elements according to correction conditions including a condition under which a power spectrum representing spatial frequency characteristics of a density non-uniformity due to recording characteristics of the plurality of recording elements has a differential coefficient of substantially zero at a frequency origin point (f=0); anda correction processing unit which performs calculation for correcting the output density according to the density correction coefficients set by the correction coefficient setting unit.

14. The image forming apparatus as defined in claim 4, wherein the image correction device comprises: a correction range setting unit which selects N correction recording elements (where N is an integer which is 2 or more) used for correcting output density, from the plurality of recording elements;a correction coefficient setting unit which sets density correction coefficients for the N correction recording elements according to correction conditions including a condition under which a power spectrum representing spatial frequency characteristics of a density non-uniformity due to recording characteristics of the plurality of recording elements has a differential coefficient of substantially zero at a frequency origin point (f=0); anda correction processing unit which performs calculation for correcting the output density according to the density correction coefficients set by the correction coefficient setting unit.

15. The image forming apparatus as defined in claim 5, wherein the image correction device comprises: a correction range setting unit which selects N correction recording elements (where N is an integer which is 2 or more) used for correcting output density, from the plurality of recording elements;a correction coefficient setting unit which sets density correction coefficients for the N correction recording elements according to correction conditions including a condition under which a power spectrum representing spatial frequency characteristics of a density non-uniformity due to recording characteristics of the plurality of recording elements has a differential coefficient of substantially zero at a frequency origin point (f=0); anda correction processing unit which performs calculation for correcting the output density according to the density correction coefficients set by the correction coefficient setting unit.

16. The image forming apparatus as defined in claim 6, wherein the image correction device comprises: a correction range setting unit which selects N correction recording elements (where N is an integer which is 2 or more) used for correcting output density, from the plurality of recording elements;a correction coefficient setting unit which sets density correction coefficients for the N correction recording elements according to correction conditions including a condition under which a power spectrum representing spatial frequency characteristics of a density non-uniformity due to recording characteristics of the plurality of recording elements has a differential coefficient of substantially zero at a frequency origin point (f=0); anda correction processing unit which performs calculation for correcting the output density according to the density correction coefficients set by the correction coefficient setting unit.

17. The image forming apparatus as defined in claim 7, wherein the image correction device comprises: a correction range setting unit which selects N correction recording elements (where N is an integer which is 2 or more) used for correcting output density, from the plurality of recording elements;a correction coefficient setting unit which sets density correction coefficients for the N correction recording elements according to correction conditions including a condition under which a power spectrum representing spatial frequency characteristics of a density non-uniformity due to recording characteristics of the plurality of recording elements has a differential coefficient of substantially zero at a frequency origin point (f=0); anda correction processing unit which performs calculation for correcting the output density according to the density correction coefficients set by the correction coefficient setting unit.