Image Forming Apparatus Velocity Ratio Control for Color Gamut
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Solution Overview
Problem
Conventional image forming apparatuses using electrophotographic methods face challenges in expanding color gamut without resulting in unnatural tinge, particularly when using additional developers or adjusting peripheral velocity ratios between the photosensitive drum and developing roller.
Innovation Solution
An image forming apparatus that switches between two operational modes: a normal mode and a wide color gamut mode, where the peripheral velocity ratio of the photosensitive drum and developing roller is altered, and image data conversion conditions are changed to achieve different gradation characteristics and color reproduction ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If developers of more than four colors (dense Y, dense M, dense C) are added to expand color gamut, then color reproduction range is improved, but device complexity increases due to additional image forming units
Solution Approach 1:
The patent changes the peripheral velocity ratio parameter between the photosensitive drum and developing roller to control toner amount and expand color gamut. By adjusting rotational speeds rather than adding components, the system achieves wider color reproduction without increasing device complexity
Solution Approach 2:
The control portion serves multiple functions: it manages both the peripheral velocity ratio adjustment and image data conversion based on different velocity ratio conditions. This multi-functionality eliminates the need for separate systems for each control task
2Manufacturing precision
If the peripheral velocity of the photosensitive drum is reduced to improve image graininess, then toner scattering is reduced, but color gamut expansion is not always achieved advantageously
Solution Approach 1:
The patent dynamically adjusts the peripheral velocity ratio between the photosensitive drum and developing roller based on the desired outcome. Rather than fixing the drum speed, the system optimizes the velocity relationship to simultaneously achieve good image graininess and expanded color gamut
Solution Approach 2:
The control portion changes image data conversion parameters based on the peripheral velocity ratio condition. When the velocity ratio is adjusted for color gamut expansion, the conversion parameters are modified to maintain natural tones and prevent unnatural tinge
3Ease of operation
If the rotation speed of the developing roller is changed to adjust secondary color tinge, then color balance is improved, but color gamut expansion is limited and unnatural tinge may occur
Solution Approach 1:
The patent comprehensively changes multiple parameters: peripheral velocity ratio, image data conversion conditions, and gradation characteristics. This multi-parameter adjustment achieves both color balance and gamut expansion while preventing unnatural tinge through coordinated optimization
Solution Approach 2:
The control portion monitors the peripheral velocity ratio condition and provides feedback to adjust image data conversion parameters accordingly. This feedback mechanism ensures that color reproduction remains natural while expanding the color gamut
Data Source
AI summary
A control portion has a conversion portion that converts image data to be used for forming a recorded image by using either a first conversion condition which has been set such as to obtain a first gradation characteristic in the image to be formed on the recording material when a first image forming operation is executed or a second conversion condition which has been set such as to obtain a second gradation characteristic, which is different from the first gradation characteristic, in the image when a second image forming operation is executed, a peripheral velocity ratio between an image bearing member and a developer bearing member being larger during the second image forming operation than during the first image forming operation, and enables the first image forming operation or the second image forming operation to be performed on the basis of converted image data.