Printhead Uniformity Compensation Using Historical Transfer Functions

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Solution Overview

Problem

Conventional methods for correcting nozzle response differences in print heads fail to adequately address non-uniformities that change over time, leading to significant spatial non-uniformities in printed images.

Innovation Solution

A printing system that includes a uniformity compensation mechanism using historical and current print image data to generate transfer functions for each pel forming element, compensating for response variations by averaging and weighting recent data more heavily to mitigate transient issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional methods for correcting each print head nozzle are used, then initial nozzle uniformity can be maintained, but non-uniformities change over time and cannot be properly fixed

Engineering Contradiction:
Improvenozzle uniformityVSAvoidtemporal consistency
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The system transitions from static correction values to dynamic correction values that are continuously updated based on recent print image data. The correction mechanism adapts over time by incorporating temporal variations in nozzle response, allowing the system to maintain accuracy despite changing conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements a feedback loop where print image data is continuously collected, analyzed, and used to update correction values. This closed-loop approach allows the system to detect and compensate for temporal drift in nozzle performance by comparing actual output against expected output and adjusting accordingly.

Inventive Principle:
Principle #23Feedback

2Productivity

If only current print data is used for correction, then processing speed is maintained, but transient issues and noise affect correction accuracy

Engineering Contradiction:
Improvecorrection processing speedVSAvoidcorrection accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The system performs preliminary corrections using historical data before applying current corrections. By pre-processing and storing correction values from previous print jobs, the system can quickly apply established correction patterns while still allowing for real-time adjustments, thus maintaining both speed and accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the weighting between historical and current data based on observed performance. When transient issues are detected, the system increases reliance on historical correction values; when stability is observed, it places more weight on current measurements, optimizing the balance between responsiveness and noise filtering.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If historical data is incorporated into correction, then temporal variations are compensated, but system complexity increases

Engineering Contradiction:
Improvetemporal consistencyVSAvoidcorrection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system creates simplified representations of complex temporal patterns by generating correction values that capture essential variation trends without storing or processing every raw measurement. These correction values serve as compressed models of nozzle behavior over time, reducing computational complexity while maintaining correction effectiveness.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The correction system is divided into modular components: data collection modules, analysis modules, correction value generation modules, and application modules. This segmentation allows each component to handle specific tasks independently, making the overall complex system more manageable and maintainable while enabling sophisticated temporal correction.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4002821B1Uniformity compensation refinement mechanism
Publication Date: 2026.04.01 RICOH CO LTD
  • EP4002821B1 patent drawingFigure 1
  • EP4002821B1 patent drawingFigure 2A
  • EP4002821B1 patent drawingFigure 2B

AI summary

A printing system is disclosed. The printing system includes at least one physical memory device to store uniformity compensation logic and one or more processors coupled with the at least one physical memory device to execute the uniformity compensation logic to receive print image measurement data corresponding with each of a plurality of pel forming elements, generate a first set of intermediate images based on the print image measurement data, determine whether historical sets of intermediate images are available, generate first transfer functions corresponding to each of the pel forming elements based on the first set of intermediate images and the historical sets of intermediate images upon a determination that the historical sets of intermediate images are available and transmit the first transfer functions for each of the pel forming elements.