BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to printing apparatuses that perform printing by forming dots on print media, to registration adjustment methods for adjusting printing positions, and to storage media.

Description of the Related Art

Japanese Patent Laid-Open No. 2013-240991 discloses a technique for serial scan inkjet printing apparatuses to make the landing positions of ink droplets ejected from print heads in agreement between printing in forward scanning and printing in backward scanning. Specifically, in the technique disclosed by Japanese Patent Laid-Open No. 2013-240991, a pattern printed in ink ejected from print heads is read, and adjustment values for making the landing positions of ink droplets in agreement are obtained based on the read results. Here, the printed pattern is read based on the density of the printed pattern. In general, the positional deviation in the landing positions of ejected ink droplets is referred to as registration. In this specification of the present application, adjustment for appropriately adjusting the positional deviations in the landing positions of ejected ink droplets is referred to as “registration adjustment” as appropriate.

Meanwhile, print heads for ejecting ink vary from each other in terms of the amount of ink in an ejected ink droplet and other characteristics due to manufacturing variation in ink characteristics, manufacturing tolerance of ejection openings, and other factors. In addition, each ejection opening changes in the amount of ink in an ejected ink droplet and other characteristics due to swelling by the ink and deterioration over time. Hence, the density of the pattern printed by such print heads may decrease.

In printing apparatuses, light color inks are used in some cases for inks such as cyan, magenta, and yellow to reduce the granularity of dots formed by ink droplets having landed on a print medium. Light color inks and yellow ink have high brightness. Accordingly, dots formed in a light color ink or yellow ink absorb less light than dots formed in other inks such as magenta ink and cyan ink. Hence, for light color inks and yellow ink, the S/N ratio of a portion where dots are formed to a portion where dots are not formed is low in optical characteristic measurement.

The technique disclosed in Japanese Patent Laid-Open No. 2013-240991, thus, has a possibility that printed pattern cannot be read accurately depending on the ink ejection conditions or the type of ink, and that accurate registration adjustment cannot be performed.

SUMMARY OF THE INVENTION

The present invention has been made in light of the above problem and provides a printing apparatus, registration adjustment method, and storage medium that are capable of performing accurate registration adjustment regardless of the ink ejection conditions and the type of ink.

In the first aspect of the present invention, there is provided a printing apparatus comprising:a print head including a nozzle through which ink is ejected and configured to print a print image by ejecting ink through the nozzle to form dots on a print medium;a measurement unit configured to measure an optical characteristic of a print image printed on a print medium;a movement unit configured to impart relative movement between a print medium and the print head;a first obtaining unit configured to obtain a first adjustment value, based on measurement result of the measurement unit measuring a first pattern that is formed on a print medium and composed of a print image printed by a predetermined print operation including the relative movement, the first adjustment value being for adjusting dot printing positions in the predetermined print operation;a second obtaining unit configured to obtain a second adjustment value, based on a second pattern printed by the predetermined print operation in a state where dot printing positions of the print head have been adjusted using the first adjustment value, the second adjustment value being for adjusting the dot printing positions at a unit of length shorter than a unit of length at which the printing positions are adjusted using the first adjustment value in the predetermined print operation; anda control unit configured to control the print head and the movement unit to make the print head and the movement unit print a print image on a print medium by the predetermined print operation while applying the first adjustment value and the second adjustment value in the control, whereinthe control unit controls the print head based on the measurement result of the first pattern measured by the measurement unit such that the print head prints the second pattern in a density according to density information on the first pattern.

In the second aspect of the present invention, there is provided a registration adjustment method comprising:a first print step of printing a first pattern by a predetermined print operation including relative movement of a print head that performs printing by ejecting ink through a nozzle to form dots on a print medium;a first measurement step of measuring the first pattern using a measurement unit capable of measuring an optical characteristic of a print image;a first obtaining step of obtaining a first adjustment value for adjusting dot printing positions in the predetermined print operation, based on first measurement result in the first measurement step;a second print step of printing a second pattern having a configuration different from the first pattern, by the predetermined print operation in a state where dot printing positions of the print head have been adjusted using the first adjustment value;a second obtaining step of obtaining, based on the second pattern, a second adjustment value for adjusting the dot printing positions at a unit of length shorter than a unit of length at which the printing positions are adjusted using the first adjustment value in the predetermined print operation; anda registration adjustment step of adjusting the dot printing positions in the predetermined print operation, based on the first adjustment value and the second adjustment value, whereinin the second print step, the second pattern is printed in a density based on density information on the first pattern, based on measurement result of the first pattern measured in the first measurement step.

In the third aspect of the present invention, there is provided a non-transitory computer readable storage medium storing a program for causing a computer to perform a registration adjustment method comprising:a first print step of printing a first pattern by a predetermined print operation including relative movement of a print head that performs printing by ejecting ink through a nozzle to form dots on a print medium;a first measurement step of measuring the first pattern, using a measurement unit capable of measuring an optical characteristic of a print image;a first obtaining step of obtaining a first adjustment value for adjusting dot printing positions in the predetermined print operation, based on first measurement result in the first measurement step;a second print step of printing a second pattern having a configuration different from the first pattern, by performing the predetermined print operation in a state where dot printing positions of the print head have been adjusted using the first adjustment value;a second obtaining step of obtaining, based on the second pattern, a second adjustment value for adjusting the dot printing positions at a unit of length shorter than a unit of length at which the printing positions are adjusted using the first adjustment value in the predetermined print operation; anda registration adjustment step of adjusting the dot printing positions in the predetermined print operation, based on the first adjustment value and the second adjustment value, whereinin the second print step, the second pattern is printed in a density based on density information on the first pattern, based on measurement result of the first pattern measured in the first measurement step.

The present invention makes it possible to perform proper registration adjustment regardless of the ink ejection conditions and the type of ink.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

