Image forming apparatus, position detection method, and computer-readable medium

Patent metadata

Field	Value
Publication number	US-11590779-B2
Application number	US-202117395364-A
Country	US
Kind code	B2
Filing date	Aug 5, 2021
Priority date	Sep 7, 2020
Publication date	Feb 28, 2023
Grant date	Feb 28, 2023

Abstract

An image forming apparatus is configured to detect, from image data of a recording medium on which a plurality of marks are printed, positions of outer edges being edges closer to ends of the image data and positions of inner edges being inside edges not closer to the ends of the image data in both of a first direction and a second direction different from the first direction; identify, with respect to a target mark for which a reference position is to be detected and two marks adjacent to the target mark, first line segments connecting positions of inner edges and second line segments connecting positions of outer edges; and detect, as a reference position of the target mark, a midpoint of a line segment connecting an intersection of the two first line segments and an intersection of the two second line segments.

First claim

What is claimed is:

1. An image forming apparatus comprising:
a printing device configured to print a plurality of marks on a recording medium;
a scanner configured to read the recording medium on which the marks are printed by the printing device; and
a CPU and memory configured to implement:
a first detecting unit configured to detect, from image data read by the scanner, positions of outer edges being edges closer to ends of the image data and positions of inner edges being inside edges not closer to the ends of the image data in both of a first direction and a second direction different from the first direction;
an identifying unit configured to identify, with respect to a target mark for which a reference position is to be detected and two marks adjacent to the target mark, first line segments connecting the positions of the inner edges and second line segments connecting the positions of the outer edges; and
a second detecting unit configured to detect, as the reference position of the target mark, a midpoint of a line segment connecting an intersection of the two first line segments connecting the positions of the inner edges and an intersection of the two second line segments connecting the positions of the outer edges.

2. The image forming apparatus according to claim 1 , wherein:
the CPU and memory are further configured to implement:
a correcting unit configured to correct image data, based on the reference position of each mark detected by the second detecting unit.

3. The image forming apparatus according to claim 1 , wherein the first detecting unit is configured to detect the positions of the outer edges and the positions of the inner edges, based on luminances before and after crossing a predetermined threshold in each of the first direction and the second direction for each mark.

4. The image forming apparatus according to claim 3 , wherein the first detecting unit detects the positions of the outer edges and the positions of the inner edges by performing linear interpolation with respect to two luminances before and after crossing the predetermined threshold in each of the first direction and the second direction for each mark.

5. The image forming apparatus according to claim 3 , wherein the first detecting unit is configured to detect the positions of the outer edges and the positions of the inner edges by curve interpolation with respect to three or more luminances before and after crossing the predetermined threshold in each of the first direction and the second direction for each mark.

6. A position detection method comprising:
printing a plurality of marks on a recording medium with a printing device;
reading the recording medium on which the marks are printed by the printing device with a scanner;
first detecting, from image data read by the scanner, positions of outer edges being edges closer to ends of the image data and positions of inner edges being inside edges not closer to the ends of the image data in both of a first direction and a second direction different from the first direction;
identifying, with respect to a target mark for which a reference position is to be detected and two marks adjacent to the target mark, first line segments connecting the positions of the inner edges and second line segments connecting the positions of the outer edges; and
second detecting, as the reference position of the target mark, a midpoint of a line segment connecting an intersection of the two first line segments connecting the positions of the inner edges and an intersection of the two second line segments connecting the positions of the outer edges.

7. A non-transitory computer-readable medium including programmed instructions that cause a computer to execute:
printing a plurality of marks on a recording medium with a printing device;
reading the recording medium on which the marks are printed by the printing device with a scanner;
first detecting, from image data read by the scanner, positions of outer edges being edges closer to ends of the image data and positions of inner edges being inside edges not closer to the ends of the image data in both of a first direction and a second direction different from the first direction;
identifying, with respect to a target mark for which a reference position is to be detected and two marks adjacent to the target mark, first line segments connecting the positions of the inner edges and second line segments connecting the positions of the outer edges; and
second detecting, as the reference position of the target mark, a midpoint of a line segment connecting an intersection of the two first line segments connecting the positions of the inner edges and an intersection of the two second line segments connecting the positions of the outer edges.

Assignees

• Hirano Noboru
• Ricoh Co Ltd

Inventors

• Hirano Noboru

Classifications

• B41J11/0045

  Guides for printing material (curl smoothing B41J11/0005; platens B41J11/02, B41J11/06; guiding webs B41J15/046) · 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

• B41J29/393

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

• B41J11/46

  by marks or formations on the paper being fed · CPC title