Image Forming Apparatus Voltage Interference Control
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Solution Overview
Problem
In electrophotographic image forming apparatuses, independent high voltage power sources connected via a common current detection circuit or grounded via a common resistor component can cause image failures due to interference, leading to issues like color shift and image defects.
Innovation Solution
An image forming apparatus with a separating mechanism that moves the developing roller to a separation position before a potentially charged area reaches the developing position, ensuring no toner is transferred onto the photosensitive drum when voltage changes occur, and utilizing a common resistor component for grounding both power sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If independent high voltage power sources are connected via a common current detection circuit, then color shift can be corrected, but image failures occur due to voltage interference between power sources
Solution Approach 1:
The invention divides the power source system into independent grounded circuits. Each high voltage power source (charging power source for black color, charging power source for color) is grounded through separate resistor components (R1, R2) to the frame ground, eliminating the common current detection circuit that caused interference. This segmentation isolates the voltage paths while maintaining individual grounding, preventing voltage changes in one circuit from affecting another.
2Adaptability or versatility
If a second power source is turned on while a first power source is in ON state, then full color mode can be activated, but charge current flows into the current detection circuit causing voltage changes
Solution Approach 1:
The invention extracts and removes the problematic common current detection circuit from the system. By eliminating this shared circuit element, the charge current from the second power source no longer flows through a path that affects the first power source's voltage output. Each power source operates with its own independent grounding path, preventing the voltage instability that occurred during mode transitions.
Solution Approach 2:
The invention implements preliminary grounding design where each power source is pre-configured with its own dedicated ground path through resistor components. This preliminary structural arrangement ensures that when mode switching occurs and the second power source is activated, the charge current has a predetermined independent path to ground, preventing any interference with the first power source's charging voltage output.
3Productivity
If charging voltage for multiple colors is applied simultaneously, then color images can be formed, but toner transfers to the photosensitive drum due to voltage changes
Solution Approach 1:
The invention segments the grounding paths for different color power sources into separate, independent circuits. Each charging power source (for black and color) has its own dedicated ground connection through separate resistor components. This segmentation prevents voltage fluctuations caused by simultaneous operation of multiple power sources, eliminating the condition that causes unwanted toner transfer to the photosensitive drum while maintaining the ability to form color images.
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 effectively prevents image failures by ensuring the developing roller is separated from the photosensitive drum during voltage changes, maintaining image quality and preventing defects such as traverse lines.
Implementation Method 1
a separating mechanism configured to move the first developing member from a contact position where the first developing member is in contact with the first photosensitive member at the developing position to a separation position where the first developing member is separated from the first photosensitive member
Implementation Method 2
the first and the second power sources are grounded via a common resistor component
Implementation Method 3
a common current detection circuit, but also in any circuit configuration in which independent high voltage power sources are grounded via a common resistor component
Implementation Method 4
first and second charging units configured to respectively charge the first and the second photosensitive members
Implementation Method 5
first and second developing members configured to cause toner to attach to the first and the second photosensitive members
Data Source
AI summary
An image forming apparatus includes a first power source configured to supply charging voltage to a first charging unit, and a second power source configured to supply predetermined voltage to at least one of a second charging unit, a second developing member, and a second transfer unit. The first and the second power sources are grounded via a common resistor component. When the second power source in a state of supplying no voltage or supplying voltage lower than the predetermined voltage at a first timing starts supplying the predetermined voltage while the first power source is supplying the charging voltage, a control unit causes a separating mechanism to move a first developing member to a separation position before a second timing at which an area of a first photosensitive member that is at a charging position at the first timing reaches a developing position.