Ink Jet Recording Head Nozzle Pattern and Rate Control
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Solution Overview
Problem
Ink jet recording apparatuses face issues with density unevenness, such as banding, due to nozzle errors and uneven ink jetting rates, which affect image quality and granularity, particularly when using halftone processing methods like dither masks.
Innovation Solution
An image processing device with a jetting rate determination unit, nozzle pattern determination unit, and conversion unit that adjusts the gradation values of pixels based on nozzle jetting rates to prevent banding without deteriorating image quality, using a combination of jetting rate determination, nozzle pattern determination, and halftone processing to control ink jetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a mask pattern is used to thin out nozzles close to the end of the nozzle array, then banding is prevented, but image granularity deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the treatment of nozzles based on their position. Specifically, nozzles close to the end of the nozzle array are given a lower jetting rate (using a mask pattern) compared to nozzles in the center, creating a non-uniform jetting rate distribution that compensates for the natural density variation caused by nozzle positioning. This local differentiation prevents banding while maintaining overall image quality.
2Object-affected harmful factors
If the jetting rate of nozzles is controlled using a dither mask, then banding is prevented, but nozzle error repetition occurs with periodic unevenness
Solution Approach 1:
The patent changes the parameter of jetting rate from a uniform value to a position-dependent variable. By setting different jetting rates for nozzles at different positions (with end nozzles having lower rates and center nozzles having higher rates), the patent prevents the periodic repetition of nozzle errors that would occur with a fixed dither mask approach. This parameter variation breaks the periodicity of error repetition.
3Extent of automation
If specific pixels are sparsely recorded to control nozzle group jetting rate, then jetting rate control is achieved, but dot distribution distortion occurs
Solution Approach 1:
The patent segments the nozzle array into different groups based on position (end nozzles vs. center nozzles) and applies different jetting rate control strategies to each segment. This segmentation allows for independent optimization of each group's contribution to the overall image, preventing dot distribution distortion while achieving the desired jetting rate control for banding prevention.
Data Source
AI summary
Provided are an image processing device, an image processing method, and an ink jet recording apparatus that can prevent the occurrence of density unevenness, such as banding, regardless of a duty, without causing deterioration of image quality. A jetting rate indicating an ink jetting rate of each of a plurality of nozzles which jet ink in a recording head including the nozzles is determined. A nozzle pattern indicating which of the plurality of nozzles of the recording head is used to record each pixel of an image on a recording medium is determined. The jetting rate of the nozzle which records each pixel is reflected in a gradation value of each pixel of the image on the basis of the determination result of the jetting rate and the determination result of the nozzle pattern to convert the gradation value of each pixel.