Image Forming Device Selective Voltage Disconnection
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Solution Overview
Problem
Conventional protective circuits in image forming devices disconnect the entire input voltage when detecting DC power, causing the device to stop operating and making it difficult to diagnose the cause of the stoppage, and requiring maintenance as the fuse blows inevitably.
Innovation Solution
An image forming device with a control unit, a first path for supplying voltage to the control unit, a second path for the heater, and a disconnection unit that selectively disconnects the heater's voltage supply based on input voltage conditions, allowing other parts to maintain voltage without disconnecting the entire input voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective circuit is provided in the input part to detect DC power and interrupt input voltage, then the device is protected from damage by abnormal voltage, but the entire device stops operating and the user cannot diagnose the cause of stoppage
Solution Approach 1:
The power supply path is divided into two separate paths: a first path for supplying voltage to the control unit and other parts, and a second path for supplying voltage to the heater. The disconnection unit is placed only in the second path, so when DC power is detected, only the heater's power supply is interrupted while the control unit continues to operate, maintaining diagnostic capability.
2Reliability
If a protective circuit with fuse is provided to interrupt input voltage when DC power is detected, then the heater is protected from damage, but maintenance work is required since the fuse blows
Solution Approach 1:
The mechanical fuse-based protective circuit is replaced with an electronic disconnection unit that can be controlled by the control unit. This electronic system can detect DC power and interrupt the second path without physically blowing a fuse, thereby eliminating the need for maintenance work while maintaining heater protection.
3Reliability
If the entire input voltage path is disconnected when DC power is detected, then the device is protected from voltage damage, but no part of the device can continue to operate for diagnosis
Solution Approach 1:
The power supply system is segmented into independent paths with selective disconnection capability. The first path remains connected to maintain control unit operation and diagnostic capability, while the second path is disconnected only when necessary to protect the heater, thus preserving information and diagnostic functions.
Data Source
AI summary
An image forming device that forms an image on a medium, includes: a heater that heats the medium; a control unit that controls the heater; a first path that receives input voltage from an external power supply, converts the input voltage into desired voltage, and supplies the desired voltage to the control unit; a second path that divides the input voltage received by the first path and supplies the input voltage to the heater; a control element that is connected to the second path and controls ON/OFF switching of the heater according to control from the control unit; and a disconnection unit that disconnects the second path depending on condition of the input voltage.