US 10,567,605 B2Granted

Image forming apparatus and calibration method

AssigneeKonica Minolta, Inc.

InventorMieko Mita

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Abstract

An image forming apparatus includes: an image former that forms a document image including a correction image; an image reader; and a calibrator, and performing correction, wherein the document image is designed so that main register marks and a subsidiary register mark are provided, and the calibrator includes a four-corner detector that detects four corners of a sheet of paper, a main register mark reference position detector that detects reference positions of the main register marks, a subsidiary register mark prediction position determiner that predicts and determines prediction positions of the subsidiary register marks, a subsidiary register mark reference position detector that detects a reference position of the subsidiary register mark, a correction image prediction position determiner that predicts and determines a prediction position of the correction image, a measured value obtainer, and a correction value calculator.

Claims16

Dependent claims

An image forming apparatus comprising:

an image former comprising a roller and that forms a document image including a correction image related to a predetermined correction function on a sheet of paper based on document image data;
a sensor that reads a sheet surface on which the document image is formed, and generates read image data;
and
a calibrator that calculates a correction value related to the predetermined correction function based on the read image data, and performs correction related to the predetermined correction function based on the calculated correction value, wherein
main register marks are provided near corners of the document image and a subsidiary register mark is provided near the correction image, and
the calibrator:
detects corners of the sheet of paper from the read image data;
detects reference positions of the main register marks near the detected corners;
predicts a position of the subsidiary register mark in the read image data from the detected reference positions of the main register marks and reference positions of the main register marks in the document image data, and determines a prediction position of the subsidiary register mark;
detects a reference position of the subsidiary register mark in a vicinity of the prediction position of the subsidiary register mark;
predicts a position of the correction image in the read image data according to the detected reference position of the subsidiary register mark and the reference position of the subsidiary register mark in the document image data, and determines a prediction position of the correction image;
obtains a measurement value of the correction image based on the prediction position of the correction image;
and
calculates a correction value based on the measurement value.

11 more elements

A calibration method of an image forming apparatus that forms a document image including a correction image related to a predetermined correction function on a sheet of paper based on document image data and that reads a sheet surface on which the document image is formed and generates read image data, the method comprising:

calculating a correction value related to the predetermined correction function based on the read image data, and performing correction related to the predetermined correction function based on the calculated correction value, wherein the document image is designed so that main register marks are provided near corners of the document image and a subsidiary register mark is provided near the correction image,
detecting corners of the sheet in the read image data;
detecting reference positions of the main register marks in a vicinity of the detected corners;
predicting a position of the subsidiary register mark in the read image data according to the detected reference positions of the main register marks and the reference positions of the main register marks in the document image data and determining a prediction position of the subsidiary register mark;
detecting a reference position of the subsidiary register mark in a vicinity of the prediction position of the subsidiary register mark;
predicting a position of a correction image in the read image data according to the detected reference position of the subsidiary register mark and the reference position of the subsidiary register mark in the document image data and determining a prediction position of the correction image;
obtaining a measurement value of the correction image based on the prediction position of the correction image;
and
calculating a correction value based on the measurement value.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/927,151Filed 21 Mar 2018
Priority: JP 2017-05754823 Mar 2017
Published: US 2018/0278757 A127 Sep 2018
Granted: 18 Feb 2020
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H04N 1/0066
Handling of original or reproduction media, e.g. cutting, separating, stacking: aligning or positioning related to handling
G06T 1/0007
General purpose image data processing: image acquisition
H04N 1/00761
Detection methods: using reference marks, e.g. on sheet, sheet holder or guide
H04N 1/0057
Handling of original or reproduction media, e.g. cutting, separating, stacking: conveying sheets before or after scanning