Capacitance-Based Toner Measurement for Image Density Control
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Solution Overview
Problem
Existing methods for detecting toner deposition on toner carrying members in image forming apparatuses face challenges in accurately measuring excessive toner amounts, leading to inconsistent image density due to fluctuations in toner specific charge and printing conditions.
Innovation Solution
A deposited-toner measuring apparatus using a toner carrying member with a toner layer removal mechanism, a first electrode forming a capacitor with the toner carrying member, and a capacitance change detector to accurately measure toner deposition by detecting changes in capacitance as the electrode moves across different areas, allowing for precise control of toner amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical detection method is used to measure toner deposition, then measurement can be performed, but measurement precision deteriorates when toner amount is excessive
Solution Approach 1:
The patent replaces the optical detection system with an electrical measurement system. Instead of using light emitting sections and light receiving elements to detect toner deposition, the invention uses a capacitor formed by a first electrode facing the toner carrying member surface. The capacitance change, which varies with toner layer thickness, is measured electrically to determine toner deposition amount. This electrical measurement method maintains accuracy across varying toner conditions where optical methods fail.
2Reliability
If toner specific charge fluctuates due to printing environment, then image density becomes inconsistent, but controlling toner deposition is required to maintain stable image quality
Solution Approach 1:
The patent implements a feedback control system where the capacitance change detector continuously monitors toner deposition amount on the toner carrying member. Based on this real-time measurement, the control unit adjusts the toner supply from the two-component developer to maintain optimal toner layer thickness. This closed-loop feedback mechanism compensates for fluctuations in toner specific charge and printing environment variations, ensuring consistent image density without requiring complex manual intervention.
3Duration of action of stationary object
If hybrid development method is used, then long service life is achieved, but toner deposition control becomes critical for maintaining image quality
Solution Approach 1:
The patent performs preliminary measurement and adjustment of toner deposition before the actual development process. The capacitance measurement system evaluates the toner layer on the toner carrying member in advance, and the control unit adjusts subsequent toner supply accordingly. This preliminary action ensures that the toner layer is optimally prepared for development, maintaining image quality consistency throughout the extended service life enabled by the hybrid development method.
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 stable image formation by accurately detecting and controlling toner deposition, minimizing fluctuations in image density and ensuring consistent image quality across varying printing conditions.
Implementation Method 1
a first electrode provided facing the surface of the toner carrying member so that the first electrode and the surface of the toner carrying member form a first capacitor, in such a position that the first electrode relatively moves, with the movement of the surface of the toner carrying member, from one to the other of positions facing the first detection area and a first reference area
Data Source
AI summary
Provided is a deposited-toner measuring apparatus capable of accurate detection of the amount of toner deposited on the toner carrying member, and an image forming apparatus equipped with the aforementioned measuring apparatus and capable of controlling the amount of toner deposited on the toner carrying member to a desired level so as to provide stable image quality at all times. A deposited-toner measuring apparatus that removes a toner layer in a part of the surface of the toner carrying member, detects change in the capacitance at the portion with a toner layer and the portion without such a toner layer, and detects the amount of the deposited toner based on the detection result of the said change in the capacitance.