Printing apparatus and printing method

• US 9,050,794 B2
• Filed: 07/15/2014
• Issued: 06/09/2015
• Est. Priority Date: 07/17/2013
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Shirakawa, Hiroaki, Suzuki, Kazuo, Nagamura, Mitsutoshi, Oikawa, Yuhei, Ishii, Yosuke
• Primary Examiner(s): NGUYEN, THINH H
• Application Number:
  US14/331,598
• Publication Number:
  US 20150022574A1
• Time in Patent Office: 329 Days
• Field of Search: 347/9, 347/12, 347 14- 15, 347/19, 347/43, 347/57
• US Class Current: 1/1
• CPC Class Codes: B41J 2/04563 detecting head temperature; Ink temperature
• CPC Class Codes: B41J 2/04565 detecting heater resistance
• CPC Class Codes: B41J 2/0458 controlling heads based on heating elements forming bubbles
• CPC Class Codes: B41J 2/0459 Height of the driving signal being adjusted
• CPC Class Codes: B41J 2/04598 Pre-pulse
• CPC Class Codes: B41J 2/07 characterised by jet control B41J2/205 takes precedence
• CPC Class Codes: B41J 29/38 Drives, motors, controls or automatic cut-off devices for the entire printing mechanism

Abstract

An inkjet printing apparatus which performs printing by performing scanning using a print head has a problem in that quality of an image of a ruled line is degraded when ink is not ejected for a certain period of time. To address this problem, control is performed such that power for driving the print head for unit regions including pixels having a ruled-line attribute becomes higher than power for driving the print head for unit regions which do not include the pixels having the ruled-line attribute. By this, a high-quality ruled-line image may be printed.

Claims

1. A printing apparatus for printing an image on a printing medium using a plurality of printing elements for generating energy used for ejection of ink, the printing apparatus comprising:

a determination unit configured to determine whether a pixel having a ruled-line attribute is included in image data of the image; and

a printing unit configured to print the image based on a result of the determination performed by the determination unit,

wherein the energy to be applied by the printing elements to the ink for printing a region including the pixel having the ruled-line attribute is higher than energy to be applied by the printing elements to the ink for printing a region which does not include the pixel having the ruled-line attribute.

2. The printing apparatus according to claim 1, wherein

a speed of ejection of ink from the printing elements to the region including the pixel having the ruled-line attribute is higher than a speed of ejection of ink from the printing elements to the region which does not include the pixel having the ruled-line attribute.

3. The printing apparatus according to claim 1, wherein

each of first and second driving pulse has a main heating pulse and a pre-heating pulse, the first driving pulse being applied to the printing elements for printing the region including the pixel having the ruled-line attribute, and the second driving pulse being applied to the printing elements for printing the region which does not include the pixel having the ruled-line attribute.

4. The printing apparatus according to claim 3, wherein

a period of time in which the pre-heating pulse included in the first driving pulse is applied is longer than a period of time in which the pre-heating pulse included in the second driving pulse is applied.

5. The printing apparatus according to claim 4, wherein

a halt time between the main heating pulse and the pre-heating pulse included in the first driving pulse is longer than a halt time between the main heating pulse and the pre-heating pulse included in the second driving pulse.

6. The printing apparatus according to claim 1, wherein

a driving voltage of the first driving pulse applied to the printing elements for printing the region including the pixel having the ruled-line attribute is lower than a driving voltage of the second driving pulse applied to the printing elements for printing the region which does not include the pixel having the ruled-line attribute.

7. A printing apparatus for printing an image on a printing medium using printing elements for generating energy used for ejection of ink, the printing apparatus comprising:

a determination unit configured to determine whether a pixel having a ruled-line attribute is included in each of a plurality of unit regions in which the image is printed;

an obtaining unit configured to obtain count numbers representing the numbers of ejected ink droplets in the individual unit regions;

a correction unit configured to correct the count numbers of unit regions determined to include the pixel having the ruled-line attribute so as to obtain values equal to or larger than a predetermined threshold value; and

a printing unit configured to print the image in accordance with the values corrected by the correction unit,

wherein energy generated by the printing elements for printing the unit regions having the count numbers equal to or larger than the predetermined threshold value is higher than energy generated by the printing elements for printing the unit regions having the count numbers smaller than the threshold value.

8. A printing apparatus for printing an image on a printing medium by performing scanning using a print head including a plurality of printing elements for generating energy used for ejection of ink, the printing apparatus comprising:

a first determination unit configured to determine whether a pixel having a ruled-line attribute is included in each of a plurality of unit regions aligned in a direction of the scanning;

an obtaining unit configured to obtain count numbers representing the numbers of ejected ink droplets in the individual unit regions;

a second determination unit configured to determine whether the count values are smaller than a predetermined threshold value for individual unit regions; and

a printing unit configured to print the image in accordance with a result of the determination performed by the first determination unit and a result of the determination performed by the second determination unit,

wherein a region of interest scanned by the print head after at least a predetermined number of consecutive unit regions having the count numbers smaller than the predetermined threshold value are detected is set, and energy generated by the printing elements used to eject ink to the region of interest when the region of interest includes a pixel having a ruled-line attribute is higher than energy generated by the printing elements used to eject ink to the region of interest when the region of interest does not include the pixel having the ruled-line attribute.

9. A printing apparatus for printing an image on a printing medium by performing scanning using a print head including a plurality of printing elements for generating energy used for ejection of ink, the printing apparatus comprising:

a first determination unit configured to determine whether a pixel having a ruled-line attribute is included in each of a plurality of unit regions aligned in a direction of the scanning;

an obtaining unit configured to obtain count numbers representing the numbers of ejected ink droplets in the individual unit regions;

a correction unit configured to correct the count numbers obtained by the obtaining unit of the unit regions determined by the first determination unit to include the pixel having the ruled-line attribute so that values equal to or larger than a predetermined threshold value are obtained;

a second determination unit configured to determine whether the count numbers of the individual unit regions are smaller than the predetermined threshold value after the correction performed by the correction unit; and

a printing unit configured to print the image in accordance with a result of the determination performed by the first determination unit and a result of the determination performed by the second determination unit,

wherein energy generated by the printing elements used to eject ink to the region of interest when the count number of the region of interest which is scanned by the print head after at least a predetermined number of consecutive unit regions having the count numbers smaller than the predetermined threshold value are detected is equal to or larger than the predetermined threshold value is higher than energy generated by the printing elements used to eject ink to the region of interest when the count number of the region of interest is smaller than the predetermined threshold value.

10. A printing method for printing an image on a printing medium using printing elements for generating energy used to eject ink, the printing method comprising:

determining whether a pixel having a ruled-line attribute is included in image data of the image to be printed on the printing medium; and

printing the image in accordance with a result of the determination,

wherein the energy to be applied by the printing elements to the ink for printing a region including the pixel having the ruled-line attribute is higher than energy to be applied by the printing elements to the ink for printing a region which does not include the pixel having the ruled-line attribute.