Density Correction Circuit for Image Forming Apparatus
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Solution Overview
Problem
Image forming apparatuses face density variations due to manufacturing tolerances causing irregular gaps between the developing roller and photoconductor drum, leading to inconsistent image development, which existing software-controlled methods struggle to correct efficiently.
Innovation Solution
An image forming apparatus with a voltage application unit providing both DC and AC voltage components, and a density correction circuit that detects variations in the AC voltage waveform to generate a control signal for the DC voltage, adjusting it to correct density variations by changing the DC voltage component accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If software control is used to detect gap variations and correct density, then density variations can be suppressed, but the number of connections between controller and developing-bias applying device increases
Solution Approach 1:
The patent introduces an AC voltage component as an intermediary signal that passes through the developing roller, photoconductor drum, and developer to become a measurement signal. This mediator enables gap detection without requiring separate sensors or additional connections to the developing-bias applying device, thus resolving the contradiction between achieving density uniformity and minimizing device complexity
Solution Approach 2:
The developing-bias applying device performs dual functions: it applies the necessary voltage for developer transport and simultaneously serves as a measurement system through the AC voltage waveform analysis. This multi-functionality eliminates the need for separate detection devices and reduces the number of connections required
2Reliability
If software control with multiple connections is used for density correction, then density variations can be detected and corrected, but processing delays increase
Solution Approach 1:
The patent replaces software-based detection and control with a hardware circuit implementation. The density correction circuit directly processes the AC voltage waveform and generates correction signals through electrical components, eliminating the processing delays inherent in software execution while maintaining correction accuracy
Solution Approach 2:
The hardware circuit enables continuous real-time monitoring and correction of density variations through the AC voltage waveform, without the discrete sampling and processing intervals that characterize software control. This continuous action eliminates processing delays and ensures immediate correction of density issues
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 approach effectively corrects density variations by adjusting the DC voltage in real-time based on AC voltage waveform changes, reducing the number of connections needed between the controller and developing-bias applying device and minimizing processing delays, thus ensuring consistent image development.
Implementation Method 1
a voltage application unit that applies, between the developer transport unit and the image carrier, a voltage, which includes a direct-current (DC) voltage component and an alternating-current (AC) voltage component and which is used for moving the developer from the developer transport unit to the image carrier
Data Source
AI summary
An image forming apparatus includes an image carrier that holds a developer image, a developer transport unit that transports a developer to the image carrier by performing a rotational movement, a voltage application unit that applies, between the developer transport unit and the image carrier, a voltage, which includes a direct-current (DC) voltage component and an alternating-current (AC) voltage component and which is used for moving the developer from the developer transport unit to the image carrier, and a density correction circuit that detects variations in a distance between the image carrier and the developer transport unit from variations in a waveform of an AC component of the voltage, which is applied by the voltage application unit, and that generates a control signal that causes the DC voltage component to change in such a manner that density variations due to the variations in the distance are corrected.