Image Density Control via Dynamic Exposure Adjustment
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Solution Overview
Problem
Existing image forming apparatuses face challenges in maintaining color stability, particularly under environmental variations, as they struggle to adjust exposure amounts and tone corrections effectively due to limitations in density variations in toner-density-detecting images, leading to potential density deviations in printed images.
Innovation Solution
An image forming apparatus with a converter, image forming unit, measuring unit, and controller that forms and measures multiple images to adjust exposure conditions dynamically, generating conversion conditions based on measurement results to optimize density adjustments and tone corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the exposure amount is greatly changed at once based on the toner-density-detecting image with the highest density, then the tone correction can be adjusted quickly, but the density variations in the highlighted portion cause larger density deviations and inhibit the correction amount from changing in time
Solution Approach 1:
The patent divides the measurement process into multiple stages: first measuring the toner-density-detecting image to get initial density information, then measuring additional images at different exposure levels to calculate appropriate correction amounts. This segmentation allows the system to avoid large single-step adjustments while still achieving timely corrections.
Solution Approach 2:
The patent performs preliminary measurements using multiple images at different exposure levels before finalizing the correction amount. By pre-measuring and calculating the relationship between exposure changes and density variations, the system can determine appropriate correction amounts that avoid excessive density deviations while maintaining adjustment speed.
2Device complexity
If the exposure amount is adjusted using the toner-density-detecting image with the highest density, then the measurement process is simplified, but the adjustment may fail to follow great environmental variations
Solution Approach 1:
The patent implements a dynamic measurement and adjustment system that adapts to environmental variations. By measuring multiple images at different exposure levels and calculating correction amounts based on the relationship between exposure changes and density variations, the system can dynamically adjust to environmental changes while maintaining a relatively simple measurement process.
Solution Approach 2:
The patent uses feedback from multiple measurement images to determine appropriate correction amounts. By continuously measuring images at different exposure levels and using the results to calculate correction amounts, the system can follow environmental variations while maintaining measurement process simplicity.
3Manufacturing precision
If multiple measurement images are always formed and measured, then the density adjustment accuracy is improved, but the productivity and time required for tone correction increase
Solution Approach 1:
The patent applies partial action by measuring multiple images only when necessary (e.g., when environmental variations are detected or during initial calibration), rather than always measuring all images. This allows the system to maintain high density adjustment accuracy when needed while preserving productivity during normal operation.
Solution Approach 2:
The patent performs comprehensive measurements preliminarily during calibration phases to establish correction relationships, then uses these pre-established relationships for faster adjustments during normal operation. This preliminary action reduces the need for repeated full measurement sequences, improving productivity while maintaining accuracy.
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 solution enables the apparatus to maintain stable image density even under significant environmental changes, ensuring consistent image quality by dynamically adjusting exposure amounts and tone corrections.
Implementation Method 1
a sensor to adjust an exposure amount for exposing the photosensitive member based on a result of detecting the density
Data Source
AI summary
A controller of an image forming apparatus calculates a density difference between a measurement result of a toner image having the highest density formed on a photosensitive drum, which is obtained by an image density sensor, and the highest density of a density target. When the density difference falls within a predetermined range, the controller generates a tone correction table based on a density value of a first toner image formed with a plurality of densities including the highest density, and sets, based on the density difference, an exposure amount of laser light to be applied to the photosensitive drum by an exposure device. When the density difference falls out of the predetermined range, the controller generates the tone correction table based on a density value of a second toner image having a larger number of tone levels than that of the first toner image.