Inkjet recording device

Patent metadata

Field	Value
Publication number	US-2020290384-A1
Application number	US-201716084134-A
Country	US
Kind code	A1
Filing date	Mar 8, 2017
Priority date	Mar 28, 2016
Publication date	Sep 17, 2020
Grant date	—

Abstract

An inkjet recording device includes: an image former; an image reader including a line sensor and an optical unit; and a conveyor. The line sensor has imaging elements, and detects incident light from a surface of a recording medium over an imaging range corresponding to arrangement of the imaging elements in a width direction intersecting a relative movement direction in which the recording medium and/or the image reader is relatively moved, thereby performing one-dimensional imaging along the width direction. The optical unit removes a high-frequency-side component that is a spatial structure equal to or higher than a predetermined cutoff frequency from spatial distribution of the incident light from the imaging range and guides the incident light to the line sensor. The cutoff frequency for the high-frequency-side component is determined to be lower in the width direction than the relative movement direction.

First claim

1 . An inkjet recording device comprising:
an image former which discharges ink from a nozzle, thereby forming an image on a recording medium; an image reader which images a surface of the recording medium; and a conveyor which moves at least one of the recording medium and the image reader, thereby relatively moving the recoding medium and the image reader in a predetermined relative movement direction, wherein the image reader includes:
a line sensor which has a plurality of imaging elements, and detects incident light from the surface of the recording medium over an imaging range corresponding to arrangement of the imaging elements in a width direction intersecting the relative movement direction, thereby performing one-dimensional imaging along the width direction; and
an optical unit which removes a high-frequency-side component that is a spatial structure equal to or higher than a predetermined cutoff frequency from spatial distribution of the incident light from the imaging range and guides the incident light to the line sensor, and
the cutoff frequency for the high-frequency-side component which is removed by the optical unit is determined to be lower in the width direction than the relative movement direction.

2 . The inkjet recording device according to claim 1 , wherein the optical unit removes the high-frequency-side component at an orientation along the width direction only.

3 . The inkjet recording device according to claim 1 , wherein the cutoff frequency in the width direction is equal to or lower than a Nyquist frequency corresponding to resolution of one-dimensional imaging data by the line sensor.

4 . The inkjet recording device according to claim 1 , wherein the optical unit includes an optical low-pass filter which removes the high-frequency-side component.

5 . The inkjet recording device according to claim 4 , wherein the optical low-pass filter is configured such that flat crystal plates each of which performs birefringence on the incident light in the width direction are laid on top of one another.

6 . The inkjet recording device according to claim 5 , wherein a separation width between an ordinary ray and an extraordinary ray of at least one of the flat crystal plates is different from the separation width of at least another one of the flat crystal plates.

7 . The inkjet recording device according to claim 5 , wherein in the optical low-pass filter, a separation width between an ordinary ray and an extraordinary ray of, among the flat crystal plates, a flat crystal plate closest to the line sensor is smaller than the separation width of a remaining flat crystal plate.

8 . The inkjet recording device according to claim 6 , wherein the separation width is determined according to an arrangement interval of the imaging elements in the width direction.

9 . The inkjet recording device according to claim 1 , wherein resolution of one-dimensional imaging data by the line sensor is determined to be smaller than recording resolution corresponding to a nozzle interval of nozzles including the nozzle in the width direction in the image former, and the recording resolution is determined to be a non-integral multiple of the resolution of the one-dimensional imaging data.

10 . The inkjet recording device according to claim 1 , comprising a hardware processor which controls a relative movement speed of the relative movement by the conveyor, wherein
the hardware processor makes the relative movement speed lower in imaging a predetermined test image with the image reader than in forming an ordinary image.

11 . The inkjet recording device according to claim 10 , wherein the hardware processor obtains, based on imaging data on the test image, position information on a position at which the ink discharged from the nozzle lands on the recording medium.

12 . The inkjet recording device according to claim 11 , wherein the hardware processor sets the relative movement speed such that a relative movement distance of the image reader and the recoding medium in an interval between times at which the line sensor performs imaging is smaller than a length of the imaging range in the relative movement direction by each of the imaging elements of the line sensor.

13 . The inkjet recording device according to claim 4 , comprising a hardware processor which, when causing the image reader to image a test image having a spatial structure cycle smaller than an arrangement interval of the imaging elements of the line sensor in the width direction, causes the optical low-pass filter to remove the high-frequency-side component from the spatial distribution of the incident light.

Assignees

• Konica Minolta Inc

Inventors

• Date Masakazu
• Mizutani Toshiyuki

Classifications

• B41J2/01

  Ink jet · CPC title

• G01N21/8901

  Optical details; Scanning details (per se G02B) · CPC title

• G06K15/027

  Test patterns and calibration (arrangements for controlling or analysing printing mechanisms of typewriters or selective printing units B41J29/393 takes precedence; colour correction using test pattern analysis in general H04N1/6033) · CPC title

• B41J2/2135

  Alignment of dots · CPC title

• B41J2/2146

  for line print heads · CPC title