Inkjet Printer Density Correction via Preliminary Measurement
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Solution Overview
Problem
Existing methods for obtaining density characteristics of printing elements in inkjet printers are costly due to the need to re-set the recording medium in the sheet feeding unit, leading to variations in ink discharge and resulting density unevenness in images.
Innovation Solution
An apparatus that corrects measured values obtained from a measurement image formed by a printing element, replacing unsuitable values with suitable ones to accurately identify density characteristics, thereby reducing density unevenness and streaks in images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the recording medium is re-set in the sheet feeding unit to obtain density characteristics, then measurement accuracy can be improved, but the cost and time consumption increase
Solution Approach 1:
The patent performs measurement of density characteristics using the recording medium before the actual printing operation. The control unit measures the density characteristics of each printing element by discharging ink dots on the recording medium and reading them with a sensor, then stores these characteristics for subsequent correction processes. This preliminary measurement eliminates the need to re-set the recording medium during operation.
Solution Approach 2:
The patent creates a digital model (density characteristics data) of the printing elements' performance by measuring ink dot density on the recording medium. This digital copy is then used for correction calculations without needing to physically re-arrange or re-set the recording medium, replacing physical manipulation with data-based correction.
2Measurement precision
If the recording medium is re-set in the sheet feeding unit to obtain density characteristics, then measurement accuracy can be improved, but manufacturing cost increases
Solution Approach 1:
The system uses the recording medium that is already present in the sheet feeding unit for measurement purposes. The control unit utilizes this existing medium to obtain density characteristics data, making the recording medium serve dual purposes: both as the substrate for measurement and as the medium for subsequent printing operations, thereby eliminating waste and additional costs.
Solution Approach 2:
The recording medium is designed to serve multiple functions: it acts as both the measurement substrate for obtaining density characteristics and the printing medium for actual image formation. This multi-functionality eliminates the need for separate measurement media, reducing costs and simplifying the manufacturing process.
3Productivity
If density characteristics are not accurately identified, then image formation speed is maintained, but density unevenness and streaks occur in the image
Solution Approach 1:
The control unit measures the actual density characteristics of each printing element by reading ink dots discharged on the recording medium with a sensor. This measured data is fed back to correct the image data before printing, compensating for variations in ink discharge among different printing elements. This feedback mechanism ensures both speed and precision without requiring manual adjustment.
Solution Approach 2:
The patent adjusts the image data parameters (ink dot density and distribution) based on the measured density characteristics of each printing element. By dynamically changing the image data parameters to compensate for printing element variations, the system maintains both high-speed operation and uniform image density without manual intervention.
Data Source
AI summary
An image processing apparatus obtains a plurality of measured values obtained by measuring a measurement image; and replaces a first measured value with a value based on a second measured value. The first measured value being included in the plurality of measured values and being unsuitable for identifying the density characteristic, and the second measured value being included in the plurality of measured values and being suitable for identifying the density characteristic.