Current Restriction Circuit for Intermediate Transfer Belt Stability
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Solution Overview
Problem
Conventional electrophotographic image forming apparatuses with intermediate transfer belts experience poor toner transfer due to fluctuations in impedance, leading to inconsistent primary transfer potentials and image density issues.
Innovation Solution
Incorporating a current restriction circuit connected to the contact member and opposing member to regulate the current flowing through the intermediate transfer belt, ensuring a predetermined primary transfer current is maintained regardless of resistance variations, using a PNP transistor and resistor configuration to control the current path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a voltage maintaining element is used to maintain constant primary transfer potential, then the primary transfer potential remains stable, but image transfer quality deteriorates when impedance fluctuates greatly
Solution Approach 1:
The invention changes the control parameter from voltage (potential) to current. Instead of maintaining constant voltage through a voltage maintaining element, the invention uses a current restricting element to maintain constant primary transfer current. This parameter change allows the system to adapt to impedance fluctuations while maintaining reliable image transfer, as current control is less sensitive to impedance variations than voltage control.
Solution Approach 2:
The invention substitutes the voltage maintaining element (electrical component) with a current restricting element that operates on different electrical characteristics. This substitution replaces a voltage-based control mechanism with a current-based control mechanism, fundamentally changing how the primary transfer unit maintains stability despite impedance fluctuations.
2Power
If current is caused to flow from secondary transfer power supply through voltage maintaining element, then primary transfer potential is generated, but current control precision is insufficient when resistance varies
Solution Approach 1:
The invention changes the controlled parameter from voltage to current in the primary transfer unit. By using a current restricting element instead of a voltage maintaining element, the system directly controls the current magnitude, achieving precise current control even when resistance values vary due to environmental factors or material properties.
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 stabilizes the primary transfer current, enhancing image transfer efficiency and maintaining consistent image density across varying environmental conditions, thereby improving the overall image forming process.
Implementation Method 1
a current restriction circuit electrically connected to the contact member and the opposing member, to restrict an amount of current flowing from the opposing member to the contact member in a case where a voltage is applied from the transfer power supply to the secondary transfer member, to a predetermined amount of current, independently of variation of resistance value of the intermediate transfer belt
Data Source
AI summary
The image forming apparatus includes a photosensitive drum, an intermediate transfer belt, a secondary transfer roller, a secondary transfer power supply, an opposing roller through which a current flows through the intermediate transfer belt when the voltage is applied to the secondary transfer roller by the secondary transfer power supply, metal rollers electrically connected to the opposing roller and contacting an inner peripheral surface of the intermediate transfer belt in vicinities of the photosensitive drums, a current restriction circuit connected to a path of a current flowing from the opposing roller to the metal rollers when the voltage is applied to the secondary transfer roller by the secondary transfer power supply, the current restriction circuit configured to restrict the current from the opposing roller to the metal rollers to a predetermined current.