Image Forming Apparatus Toner Density Control via Variable Patch Detection
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Solution Overview
Problem
Existing image forming apparatuses experience fluctuations in image density when switching from printing low to high toner ratio images, due to delayed adjustments in toner charge amounts and increased execution frequency of patch detection control, leading to productivity and toner consumption issues.
Innovation Solution
An image forming apparatus with a toner content detecting system that adjusts the target toner density ratio based on detected image density and calculates the execution frequency of adjustments, increasing frequency only when significant changes in image ratio occur, to stabilize image density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the execution frequency of patch detection control is increased to quickly respond to toner charge amount changes, then image density stability is improved, but productivity decreases and toner consumption increases
Solution Approach 1:
The patent applies dynamics by making the execution frequency of patch detection control variable rather than fixed. The control frequency is dynamically adjusted based on the current printing conditions and toner charge amount trends, executing frequently when toner charge changes are detected and less frequently when stable, thereby resolving the contradiction between reliability and productivity
Solution Approach 2:
The patent changes the parameter of control execution frequency based on detected toner charge amount variations. When the toner charge amount changes exceed a threshold, the system increases the frequency of patch detection control; when stable, it reduces frequency, thus adapting the control intensity to actual needs and avoiding unnecessary productivity loss
2Manufacturing precision
If the target TD ratio is adjusted frequently to maintain toner charge amount, then image density control is improved, but toner consumption increases
Solution Approach 1:
The patent uses feedback control by continuously monitoring image density through patch detection and adjusting the target TD ratio based on the detected density deviations. This closed-loop feedback ensures precise image density control while avoiding excessive toner supply by only making adjustments when actually needed
Solution Approach 2:
The patent performs preliminary adjustment of the target TD ratio based on predicted toner charge amount changes before they significantly affect image density. By anticipating toner charge variations and pre-adjusting the TD ratio, the system maintains better control precision while reducing the need for frequent corrective toner additions
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 solution effectively suppresses image density fluctuations and optimizes toner consumption by adjusting the execution frequency of control measures in response to changes in toner ratio, improving productivity and maintaining consistent image quality.
Implementation Method 1
the TD ratio is measured by detecting a change in apparent permeability of the developer by an inductance detecting means (i.e., an induction control method)
Data Source
AI summary
An image forming apparatus includes an image bearing member, a developing device, a toner content detecting portion, a toner supplying device, an image ratio calculating portion, a toner image density detecting portion, an adjusting portion, and a controller. The controller is configured to control an execution frequency of the adjusting portion so that execution by the adjusting portion is carried out after a number of times of image formation after occurrence of a change rate of the image ratio that is greater than a predetermined change rate reaches a first value, and execution by the adjusting portion is carried out after the number of times of image formation after occurrence of a change rate of the image ratio that is less than the predetermined change rate reaches a second value greater than the first value.