Ink Deviation Calculation Using Test Pattern Ratio

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Solution Overview

Problem

Existing image forming apparatuses face challenges in accurately calculating the actual distance of deviation in ink landing position due to fluctuations in the distance between the imaging unit and the test pattern, leading to inaccuracies in image formation.

Innovation Solution

An image forming apparatus that includes a conveyor and an imaging device forming a test pattern with a first mark and a pair of second marks, using different nozzles positioned at specific intervals, allowing the processor to calculate the actual distance of deviation by detecting the positions of these marks in the captured image and applying a ratio based on the theoretical distance between the second marks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the distance between the imaging unit and the test pattern is kept constant, then the actual distance of deviation can be accurately calculated, but the device complexity increases due to additional mechanisms required to maintain constant distance

Engineering Contradiction:
Improveaccuracy of actual distance calculationVSAvoidcomplexity of distance control mechanism
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses a two-dimensional sensor to capture an image of the test pattern, creating a digital copy of the mark positions. By analyzing the captured image data, the system calculates the actual distance of deviation without requiring physical measurement mechanisms, thus avoiding increased device complexity while maintaining calculation accuracy

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent replaces potential mechanical distance control mechanisms with an image processing approach. Instead of using complex mechanical systems to maintain constant distance, the system uses software algorithms to analyze the captured image and calculate deviation distances, substituting mechanical complexity with computational processing

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a two-dimensional sensor is used to detect mark position, then the position of deviation can be detected, but the actual distance cannot be accurately calculated when the distance between the sensor and test pattern fluctuates

Engineering Contradiction:
Improvedeviation detection capabilityVSAvoidaccuracy of actual distance calculation
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The system captures a digital image of the test pattern and uses image processing to determine both the position deviation and the scaling factor. By analyzing the relative positions of multiple marks in the captured image, the system calculates a ratio that represents the actual distance scaling, allowing accurate conversion from image coordinates to real-world distances even when the sensor-to-pattern distance varies

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent introduces a ratio parameter calculated from the captured image that dynamically adjusts for changes in distance between the imaging unit and test pattern. This ratio parameter is used to convert the two-dimensional sensor readings into accurate actual distances, allowing the system to adapt to distance fluctuations without compromising measurement precision

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3323619B1Image forming apparatus, method for calculating actual distance of deviation, and computer program product storing same
Publication Date: 2020.04.08 RICOH CO LTD
  • EP3323619B1 patent drawingFigure 1~2
  • EP3323619B1 patent drawingFigure 3~4
  • EP3323619B1 patent drawingFigure 5

AI summary

An image forming apparatus (100) includes a conveyor (150) to convey a recording medium; an image forming device (6,8,12) including a recording head (6) to form a test pattern including a first mark and a pair of second marks; an imaging device (20); and at least one processor (110,140). The processor includes a pattern forming unit (111) to cause the image forming device to form one of the first and second marks and form the other after the conveyor conveys the recording medium by a predetermined conveyance amount, a position detector (142) to detect positions of the first and second marks in the captured image, a ratio calculator (143) to calculate a ratio between a distance between the second marks and deviation of the first mark in the captured image, and a distance calculator (114) to calculate an actual distance of the deviation based on a theoretical distance between the second marks and the ratio.