Image Forming Apparatus Gradation Correction Patch Bands
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Solution Overview
Problem
Image forming apparatuses face challenges in accurately detecting gradation densities due to image unevenness and reflection unevenness, leading to inaccurate gradation correction and image stabilization control, particularly in the sub-scanning direction of the image bearing member.
Innovation Solution
The apparatus forms a plurality of patch bands at different positions in the main scanning direction on the image bearing member, each containing gradation patches in the sub-scanning direction, and uses density detection sensors to accurately detect these densities, allowing for precise gradation correction by utilizing reference patches to account for unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single patch band is formed for gradation correction, then the detection process is simple and fast, but image unevenness and reflection unevenness cause inaccurate density detection
Solution Approach 1:
The patent divides the single patch band into multiple patch bands positioned at different locations in the main scanning direction. Each patch band contains gradation patches that are detected independently, allowing the system to identify and compensate for local image unevenness and reflection unevenness affecting specific regions, thereby improving overall density detection accuracy
Solution Approach 2:
The patent introduces the main scanning direction as an additional spatial dimension for positioning multiple patch bands. By distributing patch bands across different positions in the main scanning direction rather than relying on a single location, the system captures density variations across the image bearing member's width, enabling more accurate correction of unevenness effects
2Measurement precision
If multiple patch bands are formed at different positions, then density detection accuracy improves by accounting for unevenness, but the detection process becomes more complex
Solution Approach 1:
The patent segments the density detection process by assigning specific detection tasks to each patch band location. The control section processes detection results from multiple patch bands independently, calculating output gradation levels for each band separately, which simplifies the overall complexity by breaking down the measurement process into manageable segments
Solution Approach 2:
The patent uses multiple patch bands as copies of the same gradation pattern structure, positioned at different locations. Each patch band serves as a reference copy that experiences the same types of unevenness effects, allowing the system to compare and average results across copies to improve accuracy while maintaining a standardized detection approach
3Manufacturing precision
If gradation correction is performed without accounting for image unevenness, then the correction process is fast and simple, but the output image quality deteriorates due to inaccurate gradation levels
Solution Approach 1:
The patent performs preliminary density detection across multiple patch bands before executing the gradation correction. By detecting densities at all patch band positions in advance and calculating the average output gradation levels beforehand, the system prepares correction data that accounts for image unevenness, enabling accurate correction without extending the actual image formation time
Solution Approach 2:
The patent implements a feedback mechanism where detection results from multiple patch bands are used to calculate corrected output gradation levels, which are then fed back into the image formation process. This feedback loop enables the system to automatically compensate for image unevenness and reflection unevenness, improving output image quality while maintaining efficient processing through automated correction
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
This method enables effective gradation correction and image stabilization control by accurately calculating output gradation levels, even in the presence of image and reflection unevenness, thereby improving the quality of output images.
Implementation Method 1
a reflective density detection sensor, measures the densities of the formed color gradation pattern images
Implementation Method 2
a charged photoconductor is so irradiated with laser light based on image data that an electrostatic latent image is formed
Implementation Method 3
a fixing device then heats and pressurizes the sheet to fix the toner image thereto
Data Source
AI summary
An image forming apparatus and a gradation correction method for the same are provided. An image forming apparatus includes an image forming section that forms a plurality of patch bands in a plurality of positions in a main scanning direction on an image bearing member, each of the plurality of patch bands having a plurality of gradation patches disposed in a sub-scanning direction; a density detection section that detects densities of the plurality of patch bands; and a control section that performs gradation correction based on detection results from the density detection section. The plurality of patch bands differs from each other.