Asymmetric Nozzle Array for Bidirectional Color Difference Reduction
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Solution Overview
Problem
Conventional serial type image forming apparatuses face issues with bidirectional color difference and coarse dot density, leading to deteriorated image quality, particularly when forming color images, due to deviations in droplet landing positions and limited resolution.
Innovation Solution
The apparatus employs a configuration where a black nozzle array is positioned downstream in the sub-scanning direction relative to color nozzle arrays, ensuring that black droplets are always ejected last, which reduces bidirectional color difference and improves gray quality by maintaining the predominance of earlier landed colors, while also allowing for adjustable nozzle array positions to control dot density and bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bidirectional printing is used to form color images, then productivity is improved, but bidirectional color difference occurs due to deviation in droplet landing positions
Solution Approach 1:
The patent applies asymmetry by arranging the black nozzle array and color nozzle arrays at different positions in the sub-scanning direction. Specifically, the black nozzles are positioned downstream relative to the color nozzles, creating an asymmetric configuration that ensures black droplets are always ejected after color droplets during bidirectional scanning. This asymmetric arrangement eliminates bidirectional color difference while maintaining high-speed printing capability.
2Manufacturing precision
If nozzle pitch is increased to improve dot density, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent resolves the contradiction by introducing a positional offset in the sub-scanning direction (a different dimension) rather than simply increasing the nozzle pitch in the main-scanning direction. By arranging black nozzles downstream of color nozzles in the sub-scanning direction, the patent achieves finer effective dot density and eliminates bidirectional color difference without significantly increasing device complexity or requiring denser nozzle spacing.
Data Source
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AI summary
An image forming apparatus includes a carriage that includes a head including a black nozzle array (4k2) in which a plurality of nozzles are arranged and a color nozzle array (4c) in which a plurality of nozzles are arrange, the black nozzle array (4k2) being disposed at a position shifted in the sub-scanning direction downstream in a medium conveying direction with respect to the color nozzle array (4c); a conveying unit configured to convey a recording medium in a sub-scanning direction; and a control unit. The control unit forms an image by the color nozzle array (4c) in a main scanning in one direction, relatively moves the recording medium to a subsequent main-scanning position thereafter, and forms an image by the black nozzle array (4k2) on the image formed by the color nozzle array (4c) in a following main scanning in the other direction so as to complete an image for one scanning area.