Inkjet Printer Density Correction via Frequency-Dependent Nozzle Adjustment

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Solution Overview

Problem

Inkjet printers face print quality issues due to variations in ink ejection amounts among nozzles, which are not addressed by existing density correction techniques, leading to unintentional density differences in print images.

Innovation Solution

An inkjet printer system that calculates and applies second and third density correction values based on gray-level values of pixels and previous print lines, using a controller to adjust ink ejection amounts and account for temperature variations, ensuring accurate density correction across nozzles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If existing density correction techniques are applied to correct color material density variation, then color density uniformity is improved, but ink ejection amount variation due to frequency dependence is not addressed, leading to residual density differences in print images

Engineering Contradiction:

Improvecolor density uniformityVSAvoidprint quality consistency

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent segments the density correction process into two distinct components: first, correcting color material density variation using existing techniques; second, correcting ink ejection amount variation based on frequency-dependent characteristics of each nozzle. This segmentation allows both types of variations to be addressed separately and comprehensively.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary characterization of each nozzle's ink ejection amount across different ejection frequencies before actual printing. This pre-measured frequency-dependent ejection data is stored and used to calculate correction values in advance, enabling the system to compensate for frequency effects without real-time measurement during printing.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If density correction values are calculated without considering ink ejection frequency effects, then calculation simplicity is maintained, but accuracy of density correction deteriorates due to uncorrected frequency-dependent variation

Engineering Contradiction:

Improvecorrection calculation complexityVSAvoiddensity correction accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces frequency-dependent correction values that vary based on the ejection frequency of each nozzle. Instead of using a single static correction value, the system dynamically selects or calculates correction values based on the actual ejection frequency, thereby accounting for the non-linear relationship between frequency and ejection amount.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where the actual ejection frequency of each nozzle is monitored or calculated based on printing conditions, and this frequency information is fed back into the correction value calculation process. This allows the system to adaptively adjust correction values to match actual operating conditions.

Inventive Principle:

Principle #23Feedback

3Productivity

If no frequency-based correction is applied, then processing speed is maintained, but print quality deteriorates due to unintentional density differences between adjacent areas

Engineering Contradiction:

Improveprinting speedVSAvoidprint image density uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent performs preliminary measurement and characterization of each nozzle's frequency-dependent ejection characteristics before production printing. This pre-characterization data is stored and reused during actual printing, allowing the system to apply corrections without performing real-time measurements, thus maintaining high printing speed while improving density uniformity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the correction parameter from a static value to a frequency-dependent value. By pre-calculating correction values for different frequency ranges and selecting the appropriate correction value based on actual ejection frequency, the system achieves accurate correction without real-time computational overhead, preserving printing speed.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10150301B2Inkjet printer with density correction function

Publication Date: 2018.12.11 RISO KAGAKU CORP

AI summary

A controller of an inkjet printer: calculates second density correction values for respective nozzles arranged in a predetermined direction to print a second line of an image data, by using gray-level values of pixels in the second line of the image data corresponding to the respective nozzles and first density correction values for the respective nozzles to print a first line of the image data printed immediately prior to the second line; and corrects the gray-level values of the pixels in the second line of the image data corresponding to the respective nozzles, by using the calculated second density correction values.