Power Supply Zero-Cross Detection Circuit Design
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Solution Overview
Problem
Existing power supply systems for image forming apparatuses face challenges in reducing power consumption during sleep states while maintaining accurate zero-cross detection of AC voltage, leading to increased circuit costs and complexity due to the need for multiple cutoff circuits and discharge resistors.
Innovation Solution
A power supply system that includes a first capacitor between AC voltage lines, a zero-cross detection resistor for discharging the capacitor, a zero-cross detection unit, a second capacitor between rectified AC voltage and frame ground, a discharge resistor with a lower resistance value, and a switch to control current flow, allowing for efficient power management and reduced power consumption during sleep states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple cutoff circuits are provided to reduce power consumption in sleep state, then power consumption is reduced, but circuit cost and circuit scale are increased
Solution Approach 1:
The patent combines multiple discharge resistors (first discharge resistor for X capacitor and second discharge resistor for Y capacitor) into a single circuit path controlled by one cutoff circuit. The cutoff circuit switches between connecting the first discharge resistor and the second discharge resistor based on whether zero-cross detection is needed, eliminating the need for separate cutoff circuits for each capacitor while maintaining safety and functionality.
2Use of energy by moving object
If a cutoff circuit is provided to cut off current for zero-cross detection, then power consumption in sleep state is reduced, but circuit complexity is increased
Solution Approach 1:
The single cutoff circuit performs multiple functions: it cuts off power to the zero-cross detection circuit in sleep mode, it controls the discharge path for both X and Y capacitors, and it enables zero-cross detection when needed. This multi-functional design eliminates the need for separate cutoff circuits while maintaining all required safety and operational functions.
3Reliability
If discharge resistors are provided for both X capacitor and Y capacitor, then safety is improved, but circuit cost is increased
Solution Approach 1:
The patent merges the discharge paths of both X and Y capacitors into a single controlled path using one cutoff circuit and two discharge resistors. This configuration maintains safety by ensuring both capacitors can be discharged independently through appropriate resistor selection while reducing overall circuit complexity and cost compared to having completely separate discharge circuits for each capacitor.
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
The system effectively reduces power consumption in sleep states while maintaining accurate zero-cross detection, achieving this with a simpler circuit configuration and lower costs by using a single switch to control the discharge resistors, thereby improving energy efficiency and reducing circuit complexity.
Implementation Method 1
a first capacitor provided between lines to which an AC voltage is input from an AC power supply, a zero-cross detection resistor for discharging an electric charge of the first capacitor
Implementation Method 2
a discharge resistor having a resistance value smaller than the zero-cross detection resistor and configured to discharge an electric charge of the second capacitor
Data Source
AI summary
A power supply includes a first capacitor, a resistor for discharging an electric charge of the first capacitor and for detecting zero crossing of the AC voltage input from the AC power supply, a second capacitor, and a frame ground o and a discharge resistor having a resistance value smaller than the resistor and configured to discharge an electric charge of the second capacitor, and switches between a state where a current to the discharge resistor is cut off and a state where a current flows through the discharge resistor.