Image Forming Apparatus Combined-Color Reproduction Accuracy
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in maintaining consistent developing density, particularly when printing combined colors, leading to deviations in color tones due to variations in toner concentration and charge-to-mass ratio, and require additional processes like test printouts for color measurement, which are burdensome.
Innovation Solution
An image forming apparatus with a control unit that performs a color-reproduction-accuracy increasing process by adjusting control parameters such as charge potential, latent-image writing intensity, and developing bias, and switches to a deposition-amount stabilizing process if a suitable color measurement area is not found, ensuring stable toner deposition and accurate color reproduction without the need for separate test printouts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a deposition-amount stabilizing process is performed by adjusting toner concentration based on primary color toner images, then toner deposition amount is stabilized, but combined-color reproduction accuracy deteriorates with color tones differing from desired colors
Solution Approach 1:
The patent performs color measurement on a combined-color test toner image before the main printing process. Based on the measurement results, it adjusts control parameters (charge potential, latent-image writing intensity, developing bias) in advance to compensate for deviations in combined-color reproduction. This preliminary adjustment ensures both stable toner deposition and accurate combined-color reproduction without requiring separate test printouts from users.
2Manufacturing precision
If toner is supplied in large amounts to increase toner concentration, then developing density increases, but toner charge-to-mass ratio decreases causing excessive toner deposition
Solution Approach 1:
The patent dynamically adjusts the control target value of toner concentration based on the area coverage ratio of the image to be printed. For images with high area coverage ratio, it sets a lower control target value to prevent excessive toner deposition. For images with low area coverage ratio, it sets a higher control target value to ensure sufficient developing density. This adaptive parameter adjustment optimizes both developing density and toner charge-to-mass ratio.
3Quantity of substance
If toner is supplied in small amounts to maintain low toner concentration, then toner charge-to-mass ratio increases, but developing density decreases
Solution Approach 1:
The patent adjusts the control target value of toner concentration according to the area coverage ratio. When the area coverage ratio is high, it lowers the control target value to prevent excessive toner deposition. When the area coverage ratio is low, it raises the control target value to maintain adequate developing density. This dynamic parameter adjustment resolves the contradiction between maintaining high toner charge-to-mass ratio and ensuring sufficient developing density.
4Measurement precision
If separate test printouts are required for color measurement, then color reproduction accuracy can be improved, but user convenience deteriorates due to burdensome operations
Solution Approach 1:
The patent merges the color measurement function with the normal printing process by automatically forming a combined-color test toner image on the same photosensitive element used for main image formation. The control unit coordinates the formation of test images (including combined-color images and primary color images) during the regular printing operation, eliminating the need for separate test printouts and maintaining high color reproduction accuracy while improving user convenience.
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
The apparatus achieves high accuracy in reproducing combined colors by stabilizing toner deposition and adjusting control parameters, reducing color tone deviations and eliminating the need for burdensome test printouts, thus improving print quality and user convenience.
Implementation Method 1
an electrostatic latent image, which is at a predetermined charge potential on a latent-image carrier
Implementation Method 2
carrier particles to rub against individual toner particles more actively and hence increases the toner charge-to-mass ratio
Implementation Method 3
an optical sensor measures a toner amount per unit area on the test toner image
Data Source
AI summary
An image forming apparatus includes a control unit configured to perform, if a suitable color measurement area suitable for color measurement of a combined color is found in an image, a color-reproduction-accuracy increasing process while, if not, to perform a deposition-amount stabilizing process. In the color-reproduction-accuracy increasing process, a control parameter is adjusted so as to reduce a difference between a result of the color measurement on the suitable color measurement area and a desired color. In the deposition-amount stabilizing process, a plurality of test primary-color toner images are formed by an image forming unit, and a control parameter for the image forming unit are adjusted so as to reduce a difference between each of results of toner deposition amount measurement on the test primary-color toner images and a corresponding target deposition amount.