Development Current Detection Circuit for Image Density Control
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Solution Overview
Problem
In image forming apparatuses, variations in the shape of photosensitive and development rollers lead to inconsistent development currents, causing variations in toner supply and image density, as existing systems do not account for these shape variations.
Innovation Solution
An image forming device with a current detection circuit and power supply control part that adjusts the voltage applied to the development roller to maintain a negative correlation with variations in development current, ensuring a constant toner supply and image density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant development bias is applied to the development roller and a constant charging bias is applied to the photosensitive drum, then the control system is simple, but the development current varies due to shape variations in the rollers
Solution Approach 1:
The invention introduces a feedback control mechanism where the detection circuit monitors the development current in real-time, and the power supply control part adjusts the development bias dynamically based on the detected current variations. This closed-loop feedback system compensates for shape variations in the rollers, maintaining stable development current without requiring complex mechanical precision.
Solution Approach 2:
The invention changes the development bias parameter dynamically rather than keeping it constant. By detecting variations in development current and adjusting the development bias accordingly, the system compensates for roller shape variations and maintains consistent toner supply, resolving the contradiction between simple control and current stability.
2Ease of manufacture
If the distance between the photosensitive drum and the development roller varies periodically due to shape variations, then the mechanical structure is simple, but the development current and toner supply become inconsistent
Solution Approach 1:
The feedback control mechanism detects development current variations caused by periodic distance changes due to roller shape variations. The power supply control part compensates for these variations by adjusting the development bias, ensuring consistent toner supply and image density without requiring high mechanical precision in the roller manufacturing.
Solution Approach 2:
The invention converts the harmful effect of roller shape variations into a detectable signal (development current variation) that triggers automatic compensation. By detecting the current variations and adjusting the bias accordingly, the system turns the mechanical imperfection into an opportunity for active compensation, maintaining image quality without stringent manufacturing requirements.
3Device complexity
If the development current varies due to roller shape variations, then no additional control mechanism is needed, but the toner supply amount varies and image density becomes inconsistent
Solution Approach 1:
The invention employs a feedback control system where the detection circuit monitors development current and the power supply control part adjusts the development bias based on detected variations. This relatively simple feedback loop ensures uniform toner supply and consistent image density without requiring complex mechanical precision or multiple additional components.
Solution Approach 2:
The system performs self-adjustment by automatically detecting development current variations and compensating through bias adjustment. This self-service mechanism maintains image density uniformity without requiring external intervention or complex control systems, resolving the contradiction between device simplicity and image quality consistency.
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 development current and toner supply, resulting in consistent image density across the sheet, even with periodic variations in the distance between the rollers.
Implementation Method 1
The current detection circuit detects a development current flowing between the charged photosensitive drum and the development roller
Implementation Method 2
The power supply part applies a voltage on the development roller
Implementation Method 3
The charging part charges the photosensitive drum
Data Source
AI summary
An image forming device includes a photosensitive drum, a development roller, a current detection circuit, a power supply part and a power supply control part. The development roller develops an electrostatic latent image formed on the photosensitive drum and forms a toner image on the photosensitive drum. The current detection circuit detects a development current flowing between the photosensitive drum and the development roller when the toner image is formed and outputs a detection signal showing a current value of the development current. The power supply part applies a voltage on the development roller. The power supply control part controls the power supply part such that a variation of the voltage has a negative correlation with a variation of the current value shown in the detection signal.