Printing apparatus and printing control method

Patent metadata

Field	Value
Publication number	US-9724950-B2
Application number	US-201615267481-A
Country	US
Kind code	B2
Filing date	Sep 16, 2016
Priority date	Sep 18, 2015
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

There is provided a printer including an imaging device that captures an image of a medium, and a control unit that controls an ink discharge amount of a printing unit that discharges ink to form an image. The control unit acquires a captured image of a test pattern which is obtained by an imaging device and is printed by the printing unit, and controls an ink discharge amount on the basis of a grayscale value of a first region including an outer peripheral edge of the test pattern and a grayscale value of a second region within the test pattern.

First claim

What is claimed is:

1. A printing apparatus comprising:
an imaging device that captures an image of an object; and
a control unit that controls a discharge amount of droplets of a printing unit that discharges the droplets to form an image,
wherein the control unit acquires a captured image of a test pattern formed by the printing unit from the imaging device and controls the discharge amount of the droplets on the basis of a grayscale value of a first region including an outer peripheral edge of the test pattern in the captured image and a grayscale value of a second region within the test pattern;
wherein the control unit sets a limit value of the discharge amount of the droplets;
wherein the control unit calculates an evaluation index for evaluating a difference in density between the first region and the second region on the basis of grayscale values of pixels in the first region and grayscale values of pixels in the second region, to thereby set the limit value on the basis of the evaluation index.

2. The printing apparatus according to claim 1 ,
wherein the imaging device captures an image of light through a plurality of color filters by an imaging element to thereby acquire grayscale values of a plurality of respective colors included in the plurality of color filters,
wherein the control unit sets a color variable indicating one color among the plurality of colors to be i to calculate an optical density A i of each pixel with respect to the color variable i on the basis of the grayscale values of the pixels of the first region and the second region with respect to the color variable i, and sets a coefficient with respect to the color variable i to be a i to calculate a linear sum H of each pixel by Expression (1) mentioned below, and

H
=

∑
i

⁢

a
i

⁢

A
i

(
1
)

wherein the evaluation index V is calculated as V=maxH 1 −avrH 2 when a maximum value in the linear sum of each pixel with respect to the first region is set to be maxH 1 , and an average value in the linear sum of each pixel with respect to the second region is set to be avrH 2 .

3. The printing apparatus according to claim 1 ,
wherein the imaging device captures an image of light through a plurality of color filters by an imaging element to thereby acquire grayscale values of a plurality of respective colors included in the plurality of color filters,
wherein the control unit sets a color variable indicating one color among the plurality of colors to be i to calculate an optical density A i of each pixel with respect to the color variable i on the basis of the grayscale values of the pixels of the first region and the second region with respect to the color variable i, and sets a coefficient with respect to the color variable i to be a i to calculate a linear sum H of each pixel by Expression (1) mentioned below, and

H
=

∑
i

⁢

a
i

⁢

A
i

(
1
)

wherein the evaluation index V is calculated as V=(maxH i −avrH 2 )/σ when a maximum value in the linear sum H of each pixel with respect to the first region is set to be maxH 1 , an average value in the linear sum H of each pixel with respect to the second region is set to be avrH 2 , and a standard deviation of the linear sum H of each pixel in the second region is set to be σ.

4. The printing apparatus according to claim 1 ,
wherein the control unit sets the limit value so that the evaluation index is set to be equal to or less than a threshold value.

5. The printing apparatus according to claim 4 ,
wherein when the control unit receives a threshold value change request for changing the threshold value, the control unit changes the threshold value on the basis of the threshold value change request.

6. The printing apparatus according to claim 1 , further comprising:
a movement mechanism that moves the imaging device relatively to the object in one direction.

7. The printing apparatus according to claim 6 ,
wherein the control unit calculates a pixel average value obtained by averaging the grayscale values of pixels in a direction intersecting the one direction in the captured image, to thereby control a discharge amount of the droplets on the basis of the pixel average value along the one direction.

8. The printing apparatus according to claim 6 , further comprising:
a carriage that has the imaging device and the printing unit mounted thereon,
wherein the movement mechanism moves the carriage relatively to the object along the one direction.

9. A printing control method comprising:
acquiring a captured image of a test pattern formed by discharging droplets by a printing unit;
controlling a discharge amount of the droplets in the printing unit on the basis of a grayscale value of a first region including an outer peripheral edge of the test pattern in the captured image and a grayscale value of a second region within the test pattern;
setting a limit value of the discharge amount of the droplets; and
calculating an evaluation index for evaluating a difference in density between the first region and the second region on the basis of grayscale values of pixels in the first region and grayscale values of pixels in the second region, to thereby set the limit value on the basis of the evaluation index.

Assignees

• Seiko Epson Corp

Inventors

• Kasahara Hideaki

Classifications

• B41J2/0456

  detecting drop size, volume or weight · CPC title

• B41J2/04558

  detecting presence or properties of a dot on paper · CPC title

• H04N1/6033

  using test pattern analysis (H04N1/6055 takes precedence) · CPC title

• B41J2/2121

  characterised by dot size, e.g. combinations of printed dots of different diameter · CPC title

• B41J29/393 Primary

  Devices for controlling or analysing the entire machine {; Controlling or analysing mechanical parameters involving printing of test patterns} · CPC title