Power Supply Device Voltage Rise Time Reduction
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Solution Overview
Problem
Conventional power supply devices for electrophotographic image forming apparatuses experience longer voltage rise times when series-connected, leading to density inconsistencies in images on recording paper with rough surfaces due to inadequate toner transfer.
Innovation Solution
A power supply device comprising a DC power supply, an AC power supply, and a bypass capacitor that switches from constant voltage to constant current mode when a predetermined condition is met, allowing for quicker charge storage in the bypass capacitor and reduced voltage rise time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If series-connected power supplies are used to output DC voltage, then the system can provide both DC and superimposed voltage outputs, but the voltage rise time becomes longer
Solution Approach 1:
The power supply system is divided into two independent power supply units: a DC power supply unit and an AC power supply unit. Each unit operates independently to provide its specific voltage output, eliminating the series connection configuration that caused the voltage rise time issue while maintaining the capability to provide both DC and superimposed voltage outputs.
Solution Approach 2:
A bypass capacitor is introduced as an intermediary component to charge during voltage transitions and discharge to maintain stable voltage output. This capacitor acts as a buffer that decouples the voltage rise time issue from the system's adaptability requirement, allowing rapid voltage establishment without compromising the dual voltage output capability.
2Stability of the object's composition
If DC power supply operates in constant voltage mode, then voltage stability is maintained, but voltage rise time is extended
Solution Approach 1:
The DC power supply dynamically switches between constant voltage mode and constant current mode based on operational requirements. During startup or voltage transition phases, the system operates in constant current mode to achieve rapid voltage rise. Once the target voltage is reached, it transitions to constant voltage mode to maintain stability, thus resolving the contradiction between rise time and stability.
Solution Approach 2:
The power supply employs periodic mode switching between constant voltage and constant current operation. This periodic action allows the system to optimize performance at different stages: using constant current mode for rapid voltage establishment and constant voltage mode for stable operation, thereby achieving both fast response and voltage stability.
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 reduces the start-up time and intervals between prints, enhancing print productivity and image quality by ensuring efficient toner transfer onto recording paper with varying surface roughness.
Implementation Method 1
a bypass capacitor that charges a part of a voltage that is output from the AC power supply
Data Source
AI summary
According to an aspect of the present invention, a power supply device includes: a DC power supply that outputs a DC voltage; an AC power supply that outputs any one of the DC voltage and a superimposed voltage being the DC voltage with an AC voltage superimposed thereon; and a bypass capacitor that charges a part of a voltage that is output from the AC power supply. The DC power supply starts outputting the DC voltage in a constant voltage mode and, when a predetermined condition is satisfied, switches from the constant voltage mode to a constant current mode to output the DC voltage in the constant current mode.