Printing apparatus and method of judging nozzle discharge state of printing apparatus
A printing apparatus for printing using a printhead including a plurality of nozzles, each configured to discharge ink, and a plurality of sensors, corresponding to the plurality of nozzles, for detecting a discharge state of ink from the plurality of nozzles, judges a discharge state. The apparatus prints, based on print data, an image by driving the printhead under a first drive condition to discharge the ink from the printhead to a first area, discharges ink to a second area different from the first area by driving the printhead, based on inspection data, under a second drive condition different from the first drive condition, and judges a discharge state of each nozzle by monitoring an output from each sensor at a timing of driving the printhead under the second drive condition.
1. A printing apparatus comprising:
a printhead including:
a plurality of nozzles, each configured to discharge ink, and
a plurality of sensors, corresponding to the plurality of nozzles, each configured to detect a discharge state of ink from the plurality of nozzles;
a print control unit configured to:
cause the printhead to print, based on print data, an image by driving the printhead under a first drive condition to discharge ink from the printhead, and
cause the printhead to discharge ink by driving the printhead, based on inspection data, under a second drive condition different from the first drive condition; and
a judgement unit configured to judge a discharge state of each of the plurality of nozzles, based on an output from each of the plurality of sensors at a timing of driving the printhead by the print control unit under the second drive condition.
2. The apparatus according to claim 1 , wherein
the printhead includes a plurality of heaters, corresponding to the plurality of nozzles, each configured to apply heat energy to ink to be discharged from each of the plurality of nozzles,
each of the plurality of sensors serves as a temperature sensor configured to detect a temperature of the corresponding heater,
each of the heaters and the corresponding temperature sensor are integrated in a multilayer element substrate, and
each of the temperature sensors is provided immediately below the corresponding heater in a layer different from a layer in which the corresponding heater is provided.
3. The apparatus according to claim 2 , wherein the judgement unit judges a discharge state of each of the plurality of nozzles based on a change in temperature detected by the corresponding temperature sensor.
4. The apparatus according to claim 3 , wherein if a nozzle judged, by the judgement unit, to be satisfactory exists near a nozzle judged as a failure, the print control unit causes the printhead to perform complementary printing by the nozzle judged to be satisfactory.
5. The apparatus according to claim 1 , wherein
each of the first drive condition and the second drive condition includes a drive pulse to drive the printhead, and
the drive pulse in the first drive condition is different from the drive pulse in the second drive condition.
6. The apparatus according to claim 5 , wherein the second drive condition is a drive condition that makes a discharge speed lower than a discharge speed under the first drive condition.
7. The apparatus according to claim 1 , wherein the printhead is a full-line printhead having a print width corresponding to a width of a print medium.
8. The apparatus according to claim 1 , wherein
a nozzle array formed from the plurality of nozzles is provided with a given angle with respect to a direction intersecting a conveyance direction of a print medium, and
inspection is performed from the nozzle located on a downstream side in the conveyance direction of the print medium.
9. The apparatus according to claim 8 , further comprising a storage unit configured to store a table indicating a drive pulse corresponding to the second drive condition and a drive pulse used to perform preliminary discharge from the plurality of nozzles before judgement of a discharge state by the judgement unit,
wherein the print control unit selects, based on the table, a drive pulse when judging a discharge state of each of the plurality of nozzles.
10. The apparatus according to claim 9 , wherein
in the table, a predetermined number of nozzles corresponds to a drive pulse corresponding to the second drive condition,
a number of nozzles greater than the predetermined number corresponds to one of a plurality of types of drive pulses for the preliminary discharge,
the print control unit selects a drive pulse using the table in accordance with a number of nozzles used, and
the print control unit uses the predetermined number of nozzles to judge the discharge state by the judgement unit.
11. The apparatus according to claim 8 , wherein
the print control unit:
causes the printhead to print, based on the print data, the image by driving the printhead under the first drive condition to discharge ink from the printhead to a first area, and
causes the printhead to discharge ink to a second area different from the first area by driving the printhead, based on the inspection data, under the second drive condition.
12. The apparatus according to claim 11 , wherein
the printhead forms an image by discharging the ink to a conveyed print medium, and
the first area and the second area are areas of the print medium.
13. The apparatus according to claim 12 , wherein the second area is situated on one of an upstream side and a downstream side of the first area with respect to a conveyance direction of the print medium.
14. The apparatus according to claim 12 , wherein a direction of a nozzle array formed by the plurality of nozzles is a direction intersecting a conveyance direction of the print medium.
15. The apparatus according to claim 14 , wherein if printing in the first area and printing in the second area are switched over in accordance with one of rotation of the transfer member and conveyance of the print medium, a buffer area is provided between the first area and the second area based on a distance, generated by the intersection of the nozzle array, between nozzles at two ends of the nozzle array with respect to the conveyance direction of the print medium.
16. The apparatus according to claim 15 , wherein the print control unit causes the printhead to perform, in the buffer area, preliminary discharge for a nozzle to be inspected.
17. The apparatus according to claim 8 , wherein
the printhead is driven to judge the discharge state after preliminary discharge.
18. The apparatus according to claim 8 , wherein
preliminary discharge, driving the printhead to judge the discharge state of a first nozzle, preliminary discharge, and driving the printhead to judge the discharge state of a second nozzle are performed sequentially in this order.
19. The apparatus according to claim 18 , wherein
the first nozzle and the second nozzle are not adjacent.
20. The apparatus according to claim 8 , wherein
a width of a drive pulse of the second drive condition is longer than a width of a drive pulse of the first drive condition.
21. The apparatus according to claim 8 , wherein
a total width of a drive pulse of the second drive condition is a longer than a total width of a drive pulse of the first drive condition.
22. The apparatus according to claim 8 , wherein
the printhead is of a serial type that forms an image while scanning the printhead in a direction intersecting the conveyance direction of the print medium.
23. The apparatus according to claim 8 , wherein
a drive pulse for a preliminary discharge is the same as that for printing the image.
24. The apparatus according to claim 8 , wherein
a drive pulse for a preliminary discharge is different from that for printing the image.
25. The apparatus according to claim 8 , wherein
in a case of printing the image based on the print data, when letting a width of a drive pulse for driving a first number of nozzles be a first width, and letting a width of a drive pulse for driving a second number of nozzles be a second width, the second number being greater than the first number, the second width is longer than the first width.
26. The apparatus according to claim 8 , further comprising a recovery unit having a mechanism for recovering discharge performance of the printhead, wherein
a region for printing the image, a region for preliminary discharge, and a region for the recovering by the recovery unit are arranged in a direction intersecting a conveyance direction of a print medium.
27. The apparatus according to claim 8 , further comprising a circulation unit configured to circulate ink through the printhead.
28. The apparatus according to claim 8 , further comprising a circulation unit configured to circulate ink through a liquid passageway which is provided between a reservoir storing ink and the printhead.
29. The apparatus according to claim 8 , wherein
a height of a reservoir storing ink and the printhead are designed such that the liquid surface of ink in the reservoir is positioned lower than an ink discharge surface of the printhead.
30. A method of judging a nozzle discharge state of a printing apparatus having a printhead including a plurality of nozzles, each configured to discharge ink, and a plurality of sensors, corresponding to the plurality of nozzles, each configured to detect a discharge state of ink from the plurality of nozzles, the method comprising:
printing, based on print data, an image by driving the printhead under a first drive condition to discharge the ink from the printhead;
discharging ink by driving the printhead, based on inspection data, under a second drive condition different from the first drive condition; and
judging a discharge state of each of the plurality of nozzles based on an output from each of the plurality of sensors at a timing of driving the printhead under the second drive condition.
31. The method according to claim 30 , wherein
in the printing, the image is printed, based on the print data, by driving the printhead under the first drive condition to discharge ink from the printhead to a first area, and
in the discharging, ink is discharged to a second area different from the first area by driving the printhead, based on the inspection data, under the second drive condition.
32. The method according to claim 31 , wherein
the printhead forms an image by discharging the ink to a conveyed print medium, and
the first area and the second area are areas of the print medium.
33. The method according to claim 30 , wherein
the printhead is driven to judge the discharge state after preliminary discharge.
34. The method according to claim 30 , wherein
a width of a drive pulse of the second drive condition is a longer than a width of a drive pulse of the first drive condition.
35. The method according to claim 30 , wherein
a total width of a drive pulse of the second drive condition is a longer than a total width of a drive pulse of the first drive condition.