Dual-Sensor Gradation Correction for Image Forming Apparatus
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in maintaining gradation stability due to the lack of consideration for image transfer and fixation influences, leading to unnecessary waste of sheets during gradation correction processes, which is undesirable in high-volume production printing.
Innovation Solution
An image forming apparatus equipped with two density sensors and a control section that forms and corrects toner images on both an image carrier and sheet, combining detection results from these sensors using a predetermined ratio to optimize gradation correction, reducing the number of sheets required for correction while maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gradation correction is executed by forming gradation pattern images on sheets and measuring them with a density sensor, then gradation stability on actual output sheets is ensured, but a large number of waste sheets are generated
Solution Approach 1:
The gradation correction process is segmented into two independent measurement stages: (1) measuring toner density on the image carrier (drum) before transfer, and (2) measuring toner density on the actual output sheet after transfer and fixation. This segmentation allows correction data to be obtained without consuming large numbers of sheets, as the first measurement uses the reusable image carrier.
Solution Approach 2:
The invention performs preliminary measurement of toner density on the image carrier before the transfer process. This preliminary action provides early correction data that can be used to adjust subsequent printing operations, reducing the need to consume sheets for correction purposes while maintaining final output quality.
2Productivity
If multiple density patches are formed on a single sheet for gradation correction, then the number of correction measurements can be reduced, but the sheet complexity and handling difficulty increase
Solution Approach 1:
The invention extracts the gradation measurement function from the output sheet by measuring toner density directly on the image carrier. This separation allows gradation correction to be performed independently of sheet handling, eliminating the complexity of forming multiple patches on sheets while maintaining correction efficiency.
3Ease of operation
If conventional gradation correction methods are used that only measure toner density on the image carrier, then measurement simplicity is maintained, but influences of image transfer and fixation are not considered leading to poor output sheet quality
Solution Approach 1:
The invention implements a dual-stage feedback mechanism: first measuring toner density on the image carrier to obtain initial correction data, then measuring toner density on the actual output sheet after transfer and fixation to obtain final correction data. This feedback loop ensures that both the simplicity of carrier measurement and the accuracy of output sheet measurement are utilized for comprehensive gradation 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 approach ensures gradation stability while minimizing the number of sheets needed for correction, effectively addressing the inefficiencies of traditional methods by integrating dual-sensor feedback for improved toner density management.
Implementation Method 1
a first density sensor to detect a density of the toner image formed on the image carrier
Implementation Method 2
a second density sensor to detect a density of the toner image transferred on the sheet
Data Source
AI summary
An image forming apparatus includes: an image forming section; a first density sensor; a second density sensor; and a control section to control the image forming section to form a first gradation pattern image including patches having different densities on the image carrier, to execute gradation correction of the image forming section based on a detection result obtained with the first density sensor, to control the image forming section to print a second gradation pattern image including patches having different densities on the sheet, and to execute the gradation correction based on a detection result obtained with the second density sensor, and wherein the control section adds a gradation correction result by the first density sensor to a gradation correction result by the second density sensor according to a predetermined ratio, and executes the gradation correction based on an addition result.