Image Density Calibration via Multi-Stage Pattern Reading

Solution Overview

Problem

Existing image forming apparatuses face challenges in accurately determining the target tone characteristic, leading to inconsistent color reproducibility due to variations in installation environment and component changes, which affects the quality of printed images.

Innovation Solution

The apparatus includes an image forming unit, a conveyance roller, and a reading unit, with a controller that forms and reads specific patterns on the sheet to generate data for adjusting the image density, using more data points for the first pattern than the second pattern to improve accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the target tone is determined based on a single reading of the tone adjustment image, then the calibration process is simple and fast, but the determination accuracy is low due to variations from repeated reading processing and sheet surface properties

Engineering Contradiction:

Improvetarget tone determination accuracyVSAvoidcalibration process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the calibration process into two distinct stages: a learning period where multiple tone adjustment images are read and stored, and a normal period where the stored average data is used for target tone determination. This segmentation allows the system to perform comprehensive measurements during calibration without affecting normal operation speed and accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary reading and storage of tone adjustment image data during the learning period before actual calibration is needed. By pre-processing and storing the average tone data in memory, the system eliminates the need for repeated readings during normal operation, thereby improving both accuracy and efficiency.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If multiple tone adjustment images are formed and read to improve target tone determination accuracy, then the measurement precision improves, but the time required for calibration increases

Engineering Contradiction:

Improvetarget tone determination accuracyVSAvoidcalibration time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary reading and storage of tone adjustment image data during the learning period before actual calibration is needed. By pre-processing and storing the average tone data in memory, the system eliminates the need for repeated readings during normal operation, thereby improving both accuracy and efficiency.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously accumulates tone adjustment image data during the learning period and maintains this data in memory for ongoing use. This continuous accumulation and storage approach allows the system to benefit from multiple readings without repeating the time-consuming calibration process for each measurement.

Inventive Principle:

Principle #20Continuity of useful action

3Productivity

If the tone adjustment image is formed on the same sheet as the user image in the non-image region, then waste sheets are prevented and productivity improves, but the target tone determination may be affected by sheet surface properties and reading variations

Engineering Contradiction:

Improvesheet utilization efficiencyVSAvoidtarget tone determination accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent divides the calibration process into two distinct stages: a learning period where multiple tone adjustment images are read and stored, and a normal period where the stored average data is used for target tone determination. This segmentation allows the system to perform comprehensive measurements during calibration without affecting normal operation speed and accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary reading and storage of tone adjustment image data during the learning period before actual calibration is needed. By pre-processing and storing the average tone data in memory, the system eliminates the need for repeated readings during normal operation, thereby improving both accuracy and efficiency.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11232332B2Image forming apparatus

Publication Date: 2022.01.25 CANON KK

AI summary

An image forming apparatus includes an image forming unit configured to form an image on a sheet, a conveyance roller configured to convey the sheet along a conveyance path, a reading unit which is provided on the conveyance path and is configured to read a pattern formed on the sheet, and a controller. The controller is configured to control the image forming unit to form a first pattern, control the conveyance roller to convey a sheet having the first pattern formed thereon, control the reading unit to read the first pattern, generate first data based on a result of reading the first pattern, and control the image forming unit to form a user image and a second pattern, the second pattern being formed in a region on the sheet that is different from a region in which the user image is formed.