Liquid ejection apparatus and liquid ejection method

Patent metadata

Field	Value
Publication number	US-11225092-B2
Application number	US-202016930667-A
Country	US
Kind code	B2
Filing date	Jul 16, 2020
Priority date	Jul 18, 2019
Publication date	Jan 18, 2022
Grant date	Jan 18, 2022

Abstract

A liquid ejection apparatus includes a first control unit, a light projection unit, a light reception unit, a determination unit, and a liquid ejection head. The first control unit is configured to change a threshold for determining a lifting of a recording medium conveyed along a conveyance path according to thickness of the recording medium. The light projection unit is configured to emit a detection beam for detecting the lifting of the recording medium. The light reception unit is configured to receive the detection beam. The determination unit is configured to determine the lifting of the recording medium, when the recording medium is detected with a height greater than the threshold by the detection beam. The liquid ejection head is configured to eject liquid to the recording medium.

First claim

What is claimed is:

1. A liquid ejection apparatus comprising:
a light projection unit configured to emit a detection beam for detecting a lifting of a recording medium conveyed along a conveyance path;
a light reception unit configured to receive the detection beam;
a liquid ejection head configured to eject liquid to the recording medium; and
at least one controller configured to,
detect the lifting of the recording medium conveyed along the conveyance path in response to the recording medium being detected at a height greater than a threshold by the detection beam, and
change the threshold in real time by detecting a thickness of the recording medium as the recording medium is being conveyed, and changing the threshold at a timing when the recording medium is detected at a conveyance position upstream of a position where the liquid is ejected by the liquid ejection head.

2. The liquid ejection apparatus according to claim 1 , wherein the detection beam is a linear laser having a width in a height direction.

3. The liquid ejection apparatus according to claim 1 , wherein the at least one controller is configured to receive recording medium information including the thickness of the recording medium, and refer to correspondence information indicating a correspondence relation between the recording medium information and the threshold to change the threshold.

4. The liquid ejection apparatus according to claim 1 , further comprising:
a thickness detection unit configured to detect the thickness of the recording medium, wherein
the at least one controller is configured to increase the threshold with an increase in the detected thickness.

5. The liquid ejection apparatus according to claim 1 , further comprising:
a conveyance position detection unit configured to detect the conveyance position of the recording medium.

6. The liquid ejection apparatus according to claim 1 , wherein the at least one controller is configured to,
measure time from a conveyance start timing of the recording medium, and
determine the timing to change the threshold based on the conveyance start timing.

7. The liquid ejection apparatus according to claim 1 , wherein the at least one controller is configured to stop a conveyance operation of the recording medium when the recording medium is detected with the height greater than the threshold by the detection beam.

8. A liquid ejection method comprising:
emitting a detection beam for detecting a lifting of a recording medium conveyed along a conveyance path;
receiving the detection beam;
detecting the lifting of the recording medium conveyed along the conveyance path in response to the recording medium being detected at a height greater than a threshold by the detection beam;
changing the threshold in real time by detecting a thickness of the recording medium as the recording medium is being conveyed, and changing the threshold at a timing when the recording medium is detected at a conveyance position upstream of a position where liquid is ejected; and
ejecting the liquid to the recording medium.

9. The liquid ejection apparatus according to claim 1 , further comprising:
a registration adjusting unit including,
a pair of registration rollers configured to correct an inclination in the recording medium and
a thickness detection unit downstream of the pair of registration rollers and upstream of the liquid ejection head, the thickness detection unit configured to detect the thickness of the recording medium.

10. The liquid ejection apparatus according to claim 9 , further comprising:
a conveyance position detection unit upstream of the liquid ejection head, the conveyance position detection unit configured to detect the conveyance position of the recording medium.

11. The liquid ejection apparatus according to claim 10 , wherein the conveyance position detection unit is immediately adjacent to and upstream of the liquid ejection head.

Assignees

• Kaneko Takaaki
• Inoue Kohsuke
• Ricoh Co Ltd

Inventors

• Kaneko Takaaki
• Inoue Kohsuke

Classifications

• B41J11/0035

  Handling copy materials differing in thickness (B41J11/20 takes precedence) · CPC title

• B41J11/0095 Primary

  Detecting means for copy material, e.g. for detecting or sensing presence of copy material or its leading or trailing end · CPC title

• B41J11/008

  Controlling printhead for accurately positioning print image on printing material, e.g. with the intention to control the width of margins · CPC title

• B41J2/04556

  detecting distance to paper · CPC title

• B41J11/0025

  Handling copy materials differing in width · CPC title