Phase Detector Circuit for Image Forming Apparatus Standby Power Control
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in accurately detecting the phase of alternating current (AC) power during both normal and standby modes while maintaining low power consumption, as the phase detector is placed downstream of the relay and struggles to meet the power consumption constraint in standby mode.
Innovation Solution
The apparatus includes a phase detector connected to both ends of the power cut-off unit, utilizing first and second resistor units in parallel to form different phase detection routes for normal and standby modes, with a current-phase converter using a photocoupler to output the phase signal, ensuring power consumption does not exceed 1 W in standby mode and allowing precise phase control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the phase detector is placed downstream of the relay to save power in standby mode, then power consumption is reduced, but the phase detector cannot properly detect the phase of AC power when the relay is turned off
Solution Approach 1:
The patent divides the phase detection function into two separate paths: a first path for normal mode operation and a second path for standby mode operation. The switching unit selectively activates the appropriate path based on the operational mode, allowing each path to be optimized independently for its specific function while ensuring phase detection capability in both modes.
2Measurement precision
If the phase detector is placed upstream of the relay to detect AC power phase, then phase detection is enabled, but power consumption in standby mode exceeds the predetermined limit
Solution Approach 1:
The patent implements a dynamic switching mechanism that changes the phase detection path based on the operational mode. The switching unit dynamically selects between the first path (for normal mode) and the second path (for standby mode), allowing the system to adapt its power consumption characteristics to match the current operational requirements while maintaining phase detection capability.
3Measurement precision
If conventional phase detector components (diodes and resistors) are used, then phase detection is achieved, but the power consumption constraint in standby mode cannot be satisfied
Solution Approach 1:
The patent changes the electrical parameters (resistance values, configuration) of the phase detection circuit components depending on the operational mode. By adjusting the resistance values in the first and second paths and using the switching unit to select the appropriate path, the system optimizes power consumption in standby mode while maintaining adequate phase detection performance.
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
Enables accurate phase detection and control in both modes while adhering to the power consumption constraint, allowing for operations like data backup and system reset if power is cut off, with experimental results showing reduced power consumption and precise phase control.
Implementation Method 1
a current-phase converter, H, using a photocoupler to output the phase signal
Data Source
AI summary
An image forming apparatus having a normal mode and a standby mode includes an image forming unit to form an image, a switching unit which selectively allows power to be supplied to the image forming unit, a controller to control the switching unit based on a phase signal of the power, a power cut-off unit which cuts off the power to the image forming unit in the standby mode, and a phase detector which is connected to both ends of the power cut-off unit, detects a phase of the power via different phase detection routes according to whether being in the normal mode or in the standby mode, and outputs the phase signal of the power so that a power consumption of the image forming apparatus does not exceed a predetermined value in the standby mode.