Ejection apparatus, ejection control device, and non-transitory computer readable medium storing program causing computer to execute process for controlling ejection

1. An ejection apparatus comprising:

a first ejection unit configured to eject droplets on a recording medium conveyed in a conveyance direction to form an image for detection on the recording medium;

a first detection unit disposed downstream of the first ejection unit in the conveyance direction and configured to detect the image for detection;

a second detection unit disposed downstream of the first detection unit in the conveyance direction and configured to detect the image for detection;

a second ejection unit disposed downstream of the first detection unit in the conveyance direction and configured to eject droplets on the recording medium; and

a control unit configured to:

predict a first elongation amount of the recording medium in the conveyance direction based on a first difference between a first set time period and a first detection time period from a reference time point to a first detection time point when the first detection unit detects the image for detection, and further based on a second difference between a second set time period and a second detection time period from the first detection time point to a second detection time point when the second detection unit detects the image for detection; and

perform delay control on the second ejection unit for delaying an ejection timing of the second ejection unit based on the predicted elongation amount.

2. The ejection apparatus according to claim 1 ,

wherein the second detection unit is disposed downstream of the second ejection unit in the conveyance direction.

3. The ejection apparatus according to claim 2 ,

wherein the recording medium comprises a plurality of pages,

the first ejection unit is configured to form the image for detection on a predetermined page of the recording medium, and

the control unit is configured to perform the delay control for the ejection timing of the second ejection unit when the second ejection unit performs ejection on a next page upstream of the predetermined page in the conveyance direction.

4. The ejection apparatus according to claim 1 ,

wherein the second detection unit is disposed on an upstream of the second ejection unit in the conveyance direction.

5. The ejection apparatus according to claim 4 , further comprising:

a third ejection unit disposed downstream of the first detection unit and upstream of the second detection unit in the conveyance direction and configured to eject droplets on the recording medium.

6. The ejection apparatus according to claim 5 ,

wherein the control unit is further configured to perform a delay control on the third ejection unit for delaying an ejection timing of the third ejection unit based on the predicted elongation amount.

7. An ejection apparatus comprising:

a first ejection unit configured to eject droplets on a recording medium conveyed in a conveyance direction to form an image for detection on the recording medium;

a first detection unit disposed downstream of the first ejection unit in the conveyance direction and configured to detect the image for detection;

a second ejection unit disposed downstream of the first detection unit in the conveyance direction and configured to eject droplets on the recording medium; and

a control unit configured to:

predict a first elongation amount of the recording medium in the conveyance direction based on a first difference between a first set time period and a first detection time period from a reference time point to a first detection time point when the first detection unit detects the image for detection, wherein the reference time point is a time point when the first ejection unit ejects droplets to form the image for detection on the recording medium; and

perform delay control on the second election unit for delaying an ejection timing of the second ejection unit based on the predicted elongation amount.

8. An ejection control device comprising:

a processor configured to:

predict an elongation amount of a recording medium conveyed in a conveyance direction based on a first difference between a first set time period and a first detection time period from a time point when a first ejection unit ejects droplets to form an image for detection on the recording medium to a first detection time point when a first detection unit detects the image for detection, and further based on a second difference between a second set time period and a second detection time period from the first detection time point to a second detection time point when a second detection unit detects the image for detection, the second ejection unit being disposed downstream of the detection unit in the conveyance direction; and

perform delay control for delaying an ejection timing from a second ejection unit disposed downstream of the detection unit in the conveyance direction based on the predicted elongation amount.

9. The ejection control device according to claim 8 ,

wherein the recording medium comprises a plurality of pages,

the first ejection unit is configured to form the image for detection on a predetermined page of the recording medium, and

the processor is configured to perform the delay control for the ejection timing of the second ejection unit when the second ejection unit performs ejection on a next page upstream of the predetermined page in the conveyance direction.

10. The ejection control device according to claim 9 ,

wherein the control unit is further configured to perform a delay control on a third ejection unit for delaying an ejection timing of the third ejection unit based on the predicted elongation amount, the third ejection unit being disposed between the first detection unit and the second detection unit in the conveyance direction and configured to eject droplets on the recording medium.