Apparatus for and method of recording image
An image recording apparatus includes a plurality of recording heads arranged in a staggered configuration in a width direction. Adjacent ones of the recording heads have respective adjacent nozzles for ejecting ink droplets onto positions adjacent to each other in the width direction on a recording medium. For recording an image, a correction area rate less than a dot area rate of an input mage in a recording position of each of the adjacent nozzles is calculated from the dot area rate. Then, ink droplets are ejected from each of the adjacent nozzles in accordance with the correction area rate. As a result, the amounts of ink droplets ejected from the adjacent nozzles are limited. For a recording process using a head unit including the recording heads arranged in a staggered configuration, this suppresses the occurrence of unevenness in density due to an undesirable flow or bleeding of ink at the boundary between recording regions of the recording heads.
1. An image recording apparatus for recording an image by ejecting ink droplets onto a sheet-like recording medium, comprising:
a transport mechanism for transporting said recording medium along a transport path;
a head unit for ejecting ink droplets toward said recording medium transported by said transport mechanism; and
a controller for controlling said transport mechanism and said head unit,
said head unit being structured to include a plurality of recording heads each having a plurality of nozzles arranged in a width direction orthogonal to said transport path, said recording heads being arranged in a staggered configuration in said width direction,
said recording heads in said head unit including adjacent recording heads having respective adjacent nozzles for ejecting ink droplets onto positions adjacent to each other in said width direction on said recording medium,
said controller causing each of said adjacent nozzles to eject ink droplets in accordance with a correction area rate less than a dot area rate of an input image in a recording position of each of said adjacent nozzles.
2. The image recording apparatus according to claim 1 , wherein
said controller calculates said correction area rate by multiplying the dot area rate of the input age in the recording position of each of said adjacent nozzles by a previously determined correction coefficient, and
said correction coefficient remains the same or decreases as said dot area rate increases.
3. The image recording apparatus according to claim 2 , wherein
said controller includes
a storage part for rewritably storing therein table data in which values of said correction coefficient corresponding to values of said dot area rate are determined for each of said adjacent nozzles.
4. The image recording apparatus according to claim 3 , wherein
said table data further specifies the number of nozzles to be controlled as said adjacent nozzles between the recording heads.
5. The image recording apparatus according to claim 1 , wherein
said controller causes the adjacent nozzle of one of said adjacent recording heads to eject ink droplets in accordance with said correction area rate, and
said controller causes the adjacent nozzle of the other of said adjacent recording heads to eject ink droplets in accordance with said dot area rate.
6. A method of recording an image by ejecting ink droplets from a head unit toward a sheet-like recording medium while transporting said recording medium along a transport path, said head unit including a plurality of recording heads arranged in a staggered configuration in a width direction orthogonal to said transport path, each of said recording heads having a plurality of nozzles arranged in said width direction, said recording heads in said head unit including adjacent recording heads having respective adjacent nozzles for ejecting ink droplets onto positions adjacent to each other in said width direction on said recording medium, said method comprising the steps of:
a) calculating a correction area rate from a dot area rate of an input image in a recording position of each of said adjacent nozzles, said correction area rate being less than said dot area rate; and
b) ejecting ink droplets in amounts depending on said correction area rate from each of said adjacent nozzles, said step b) being performed after said step a).
7. The method according to claim 6 , wherein
said correction area rate is calculated in said step a) by multiplying the dot area rate of the input image in the recording position of each of said adjacent nozzles by a previously determined correction coefficient, and
said correction coefficient is set so as to remain the same or to decrease as said dot area rate increases.
8. The method according to claim 7 , further comprising the steps of:
c) storing table data in which values of said correction coefficient corresponding to values of said dot area rate are determined for each of said adjacent nozzles in a storage part, said step c) being performed before said step a); and
d) reading said table data from said storage part to determine said correction coefficient for use in said step a), said step d) being performed after said step c) and before said step a).
9. The method according to claim 8 , further comprising the step of:
e) rewriting said table data in said storage part.
10. The method according to claim 9 , wherein
said table data further specifies the number of nozzles to be controlled as said adjacent nozzles between the recording heads.