Image Forming Apparatus Toner Density Control
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Solution Overview
Problem
Existing image forming apparatuses face challenges in maintaining optimal toner charge levels, particularly at extreme temperature and humidity conditions, leading to deteriorated image quality due to insufficient control over the toner-to-carrier ratio, resulting in issues like spot-like uneven transfers and toner adhesion.
Innovation Solution
An image forming apparatus with a control unit that sets a target toner density based on detected image density and adjusts the toner supply and transfer conditions, including primary and secondary transfer portions, to maintain optimal toner-to-carrier ratios within predetermined limits, thereby stabilizing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If toner density is increased to maintain fixed toner charge, then toner loading amount is reduced and image density is lowered, but friction opportunity of developer is reduced which lowers toner charge
Solution Approach 1:
The patent employs feedback control by detecting the actual toner charge level and adjusting the toner supply amount accordingly. The control unit continuously monitors toner charge and modifies toner supply to maintain the target toner charge level, creating a closed-loop system that resolves the contradiction between maintaining stable toner charge and ensuring consistent image density.
Solution Approach 2:
The patent dynamically adjusts the toner supply parameter based on detected toner charge levels. By changing the toner supply rate in response to measured charge variations, the system maintains optimal toner charge stability while preventing image density fluctuations, thus resolving the contradiction between charge stability and density consistency.
2Manufacturing precision
If toner density is decreased to increase toner loading amount for higher image density, then image density rises, but friction opportunity of developer is increased which raises toner charge
Solution Approach 1:
The feedback control mechanism detects increased toner charge resulting from higher friction opportunity and reduces toner supply accordingly. This continuous monitoring and adjustment prevents toner charge instability while maintaining the desired image density, resolving the contradiction between these two parameters.
Solution Approach 2:
The system dynamically adjusts the toner supply parameter downward when toner charge exceeds the target level, even if image density is high. This parameter change ensures toner charge stability is maintained without compromising image quality, resolving the contradiction between image density and charge stability.
3Reliability
If inductance control is used alone to maintain toner density, then toner charge is controlled, but detection delay occurs when large amount of toner is consumed, causing toner density to drop unexpectedly
Solution Approach 1:
The patent supplies toner in advance based on predicted consumption patterns before the actual toner density drops. This preliminary action prevents the detection delay problem by proactively replenishing toner, ensuring continuous optimal toner charge control without waiting for delayed detection signals.
Solution Approach 2:
The system dynamically adjusts toner supply timing and amount based on real-time detection results. By making the control responsive and adaptive rather than static, the system compensates for detection delays and maintains accurate toner charge control even during periods of high toner consumption.
4Reliability
If target toner density is set arbitrarily to maintain fixed toner charge, then toner supply is controlled, but carrier charging property deteriorates by attachment of toner to carrier surface, causing toner charge to gradually deteriorate with durability
Solution Approach 1:
The feedback control mechanism detects gradual deterioration of toner charge due to carrier surface attachment and adjusts toner supply parameters accordingly. By continuously monitoring and responding to charge level changes, the system compensates for durability-related degradation and maintains stable toner charge over extended operational periods.
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 optimizes toner supply and transfer conditions to prevent toner charge imbalances, ensuring consistent image quality even under varying environmental conditions by dynamically adjusting transfer currents based on detected image density.
Implementation Method 1
magnetic permeability is detected using an inductance sensor, a signal corresponding to the toner density is output
Implementation Method 2
a control using an optical sensor configured to detect a specular reflection light amount of LED light reflected on a patch image
Implementation Method 3
a control using a video count unit configured to count and add up the total number of developed dots of the whole binary-modulated image supplied to a light source
Implementation Method 4
having a transfer body configured to form a transfer portion with an image bearing member to form an image on a recording material by applying an electro-photographic system or an electrostatic recording system
Data Source
AI summary
An image forming apparatus includes an image bearing member, a developing apparatus, a toner supply portion, a toner density detection portion, an intermediate transfer body, a secondary transfer body, an image density detection unit, and a control unit. The control unit sets a transfer condition of at least either a primary transfer portion or a secondary transfer portion based on an image density being detected by the image density detection unit in a state where a target toner density set based on the image density being detected reaches a limit value of a predetermined setting range.