Inkjet Nozzle Position Detection via Void Pattern
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Solution Overview
Problem
Conventional inkjet printing apparatuses face challenges in accurately determining nozzle positions due to indistinct image reading and reduced accuracy caused by flare and ink discharge deviation, especially when using scanners with resolutions equivalent to or lower than the recording resolution, leading to difficulties in head shading and density measurement.
Innovation Solution
An inkjet image recording apparatus with a chart that includes a density detecting pattern and position detecting marks formed by suspending discharge from specific nozzles, allowing for accurate determination of nozzle positions and reduced area printing, utilizing a CCD image sensor to read and correct ink discharge amounts based on image data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the position detecting pattern is formed outside the density detecting pattern, then the nozzle positions can be detected, but the margin area for printing the chart becomes narrow and may not fit on standard paper sizes
Solution Approach 1:
The patent merges the position detecting pattern with the density detecting pattern by forming position detecting marks within the density detecting pattern area. Specifically, certain nozzles are suspended from discharge to form position detecting marks (white marks) directly on the density detecting pattern, eliminating the need for separate position detecting pattern areas and reducing overall chart size.
Solution Approach 2:
The position detecting marks are nested within the density detecting pattern area. The position detecting marks are formed as specific regions (e.g., suspended discharge regions) that are contained within the broader density detecting pattern, allowing both functions to coexist in the same space.
2Measurement precision
If ink is discharged from one particular nozzle to form the position detecting pattern on white paper, then nozzle positions can be detected, but the image becomes indistinct due to flare
Solution Approach 1:
Instead of forming position detecting marks by discharging ink (dark marks on light background), the patent inverts the approach by suspending discharge from specific nozzles to create white marks (light regions on dark background) within the density detecting pattern. This inversion eliminates flare issues while maintaining detection accuracy.
Solution Approach 2:
The patent utilizes contrast reversal by creating position detecting marks as suspended discharge regions (appearing as light/white marks) against the background of discharged ink density areas. This color/contrast change from dark-on-light to light-on-dark eliminates the flare problem inherent in conventional approaches.
3Measurement precision
If a scanner with resolution higher than recording resolution is used to read the position detecting pattern, then accurate position determination is possible, but the device complexity and cost increase
Solution Approach 1:
The patent changes the parameters of the position detecting marks by forming them as suspended discharge regions within density areas, creating high-contrast marks that can be accurately detected even by scanners with resolution equivalent to recording resolution. This parameter change in mark formation method eliminates the need for higher resolution scanners.
4Measurement precision
If the discharge rate is varied to form density areas, then head shading correction can be performed, but the ink discharge amount control becomes more complex
Solution Approach 1:
The patent performs preliminary actions by forming the density detecting pattern with multiple density areas corresponding to different discharge rates before conducting head shading correction. The position detecting marks are also formed in advance by suspending discharge from specific nozzles. This preliminary pattern formation provides all necessary data for accurate head shading correction without requiring complex real-time control during the correction process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate determination of nozzle positions and reduces the area required for printing, maintaining high accuracy in head shading even with scanners at recording resolution, by forming position detecting marks within the density detecting pattern and using image data for discharge correction.
Implementation Method 1
utilizing a CCD image sensor to read and correct ink discharge amounts based on image data
Data Source
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AI summary
A chart 50 is formed of a density detecting pattern 51 and position detecting marks 52. The density detecting pattern 51 includes five different density areas A, B, C, D and E in form of belts arranged sequentially in Y-direction. The position detecting marks 52 are formed at intervals in X-direction which is a direction of arrangement of nozzles, at an end of the density area A of the density detecting pattern 51. These position detecting marks 52 are formed by suspending, for a fixed period of time, discharge from particular nozzles selected from a plurality of nozzles which discharge ink for forming the density detecting pattern 51, thereby producing ink-free portions (void portions) in the density area A.