Interlock Switch for High Voltage Power Cutoff
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Solution Overview
Problem
Existing image forming apparatuses face challenges in efficiently cutting off power from high voltage loads while maintaining a simple configuration, particularly when dealing with multiple high voltage generating units with different voltages, and require complex control circuits to manage inrush currents.
Innovation Solution
The implementation of a high voltage generating power supply system that includes a first and second low voltage power supply, switching elements, transformers, and a control unit that uses an interlock switch to disconnect power from high voltage loads when the cover is opened, generating oscillating currents to boost voltages and control the switching elements via a CPU, allowing for simple power cutoff from both low and high voltage loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a switching element with PWM control is used to cut off power from high voltage loads, then inrush current is reduced, but the control circuit becomes complicated
Solution Approach 1:
The patent extracts the power cutoff function from the complex PWM control circuit and implements it through a simple interlock switch that physically disconnects the power supply line when the cover is opened. This removes the need for complicated control circuits while still achieving the goal of reducing inrush current by preventing power from being supplied to high voltage loads during cover-open conditions
Solution Approach 2:
The interlock switch acts as an intermediary device between the cover opening detection and the power supply system. Instead of using complex electronic control, the mechanical interlock switch directly opens the power circuit when the cover is opened, providing a simple and reliable method to prevent inrush current without requiring complicated control logic
2Reliability
If separate interlock switches are provided for each power supply line (5V and 24V), then power cutoff reliability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the power cutoff function for multiple power supply lines (5V for LD and 24V for motor) into a single interlock switch. This single switch controls the common power supply line that feeds both voltage levels, achieving reliable power cutoff for all high voltage loads simultaneously while reducing the number of switches from two to one, thereby decreasing device complexity
3Speed
If power is continuously supplied to high voltage loads, then operational readiness is improved, but energy consumption increases
Solution Approach 1:
The interlock switch is pre-configured to automatically disconnect power from high voltage loads when the cover is opened, even before the system detects the cover-open state through software. This preliminary mechanical action immediately stops power consumption to high voltage loads while the system is still operational, achieving both energy saving and maintained operational readiness when the cover is closed
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 enables the efficient and simple disconnection of power from multiple high voltage generating units with different voltages, reducing the risk of inrush currents and preventing damage to components like the LD driver IC, while conserving energy by minimizing power consumption during standby modes.
Implementation Method 1
a first transformer which is included in the first high voltage generating unit and generates the first high voltage by boosting a second low voltage higher than the first low voltage based on the first oscillating current
Data Source
AI summary
An image forming apparatus includes, an image forming unit, an irradiating unit, a first low voltage power supply which generates a first low voltage, a first low voltage power supply line, a first switching element, a first high voltage generating unit including a first transformer, a second low voltage power supply, and a control unit. The image forming apparatus further includes a cover which can be opened and closed, wherein the image forming unit detects the opening and closing of the cover; and an interlock switch which interlocks with the opening/closing of the cover and includes a first contact point connected to the first low voltage power supply and a second contact point connected to the first low voltage power supply line, wherein the interlock switch is opened to disconnect the first contact point from the second contact point when the cover is opened.