Electrophotographic Potential Control via Charge Transfer Sensing
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Solution Overview
Problem
Existing electrophotographic apparatuses face challenges in maintaining image quality stability due to changes in environmental conditions and repeated use, leading to fluctuations in photosensitive member surface potential, which affect image density, and current methods for controlling surface potential either increase apparatus size and cost or require complex procedures.
Innovation Solution
An electrophotographic apparatus with a charge transfer amount-sensing unit and exposed portion potential-controlling unit that senses charge transfer per unit time and controls potential based on specific electrical characteristics of the photosensitive member, using a normalized radius of curvature to stabilize image exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surface potentiometer is arranged to directly measure the surface potential of the photosensitive member, then image quality stability is improved, but the apparatus size and cost increase
Solution Approach 1:
The patent uses the transfer roller to indirectly measure surface potential through current measurement during the transfer process, rather than directly measuring potential with a potentiometer. This copying approach allows potential control without adding complex measurement equipment to the apparatus.
Solution Approach 2:
The transfer roller serves as an intermediary element that enables surface potential measurement through current measurement during the transfer process. By using the existing transfer roller as the measurement interface, the patent avoids adding separate potentiometer equipment while still achieving potential control.
2Reliability
If correction procedures are followed to determine surface potential from current values, then surface potential control is achieved, but the control procedure becomes complicated and time-consuming
Solution Approach 1:
The patent implements a feedback mechanism where the current measurement during transfer directly informs surface potential control adjustments. The control unit uses the measured current value to automatically adjust charging conditions, creating a closed-loop system that simplifies the control procedure while maintaining accuracy.
Solution Approach 2:
The transfer process itself serves dual purposes: both transferring the toner image and measuring the surface potential through current measurement. This self-service approach eliminates the need for separate measurement and control procedures, simplifying the overall control process.
3Measurement precision
If traditional surface potential measurement methods are used, then accurate potential control is achieved, but the measurement and control process takes too much time
Solution Approach 1:
The patent merges the surface potential measurement function with the existing transfer process. By measuring current during the transfer operation rather than performing separate measurement steps, the system achieves accurate potential measurement without adding time loss, as both functions occur simultaneously.
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 allows for precise control of photosensitive member potential in a short time period with high accuracy, maintaining image quality stability while reducing apparatus size and cost.
Implementation Method 1
such a voltage that a high voltage is applied to the charging roller, and hence discharge starts to occur between the roller and the photosensitive member
Implementation Method 2
an electrostatic latent image is formed on the photosensitive member with an image-exposing unit such as a laser scanner
Implementation Method 3
sensing an amount of charge transferred to the electrophotographic photosensitive member per unit time at a time of charging of the exposed portion
Data Source
AI summary
The electrophotographic apparatus includes: an electrophotographic photosensitive member; a charging unit; an image-exposing unit; a charge transfer amount-sensing unit for sensing the amount of charge transferred to the electrophotographic photosensitive member; and an exposed portion potential-controlling unit for controlling the potential of each of the exposed portions of the electrophotographic photosensitive member based on a sensing result, which is obtained by charging the electrophotographic photosensitive member with the charging unit, performing image exposure with the image-exposing unit in at least one light amount weaker than a light amount in which the normalized radius of curvature R of the electrophotographic photosensitive member represented by the following equation (E1), the normalized radius of curvature being obtained by a method of measuring an EV curve, shows a minimum, and in at least two light amounts stronger than the light amount in which the normalized radius of curvature shows the minimum.R=[1+(dydx)2]3/2<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[LeftBracketingBar]"</annotation></semantics>d2ydx2<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[RightBracketingBar]"</annotation></semantics>(E1)