Power Control for Image Forming Apparatus After Abnormal Power Failure

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Solution Overview

Problem

Existing image forming apparatuses face issues with data loss and power wastage due to unexpected power failures, as they lack a reliable method to maintain the previous power status and require additional microcomputers for effective power control, increasing costs and complexity.

Innovation Solution

An image forming apparatus with a switching circuit unit and a controller that stores and retrieves power status information using a non-volatile memory, allowing the apparatus to maintain the last power status and control power supply without a mechanical switch, thereby preventing data loss and power wastage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a mechanical switch is used to control AC power of the primary circuit, then power control is achieved, but the AC harness must be connected from back side to front side causing design problems and increased production costs

Engineering Contradiction:

Improvepower controlVSAvoidharness connection

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical switch controlling AC power with an electronic switching circuit unit that controls DC power in the secondary circuit. This substitution eliminates the need for complex AC harness connections while achieving the same power control function through electronic means (transistor-based switching circuit).

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention extracts the power control function from the primary circuit (AC side) and relocates it to the secondary circuit (DC side). By taking out the switching function and placing it in the secondary circuit, the patent avoids the complexity of AC harness routing while maintaining user-friendly power control.

Inventive Principle:

Principle #2Taking out (Extraction)

2Ease of operation

If a mechanical switch is used for power control, then power can be turned off, but data may be lost and logic circuits may be damaged due to unexpected power-off

Engineering Contradiction:

Improvepower off capabilityVSAvoiddata protection

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent implements preliminary action by providing a standby power supply that continuously powers the controller and memory even when the main power is off. This preliminary power supply ensures that data can be backed up and power status can be recorded before any unexpected power failure occurs, protecting against data loss and circuit damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention provides beforehand cushioning through the standby power supply and power failure detection circuit. These components are prepared in advance to detect power failures and initiate data backup operations, cushioning the system against the harmful effects of unexpected power-off events.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If the image forming apparatus is set to turn on after power failure, then power is supplied, but power is wastefully consumed if not needed

Engineering Contradiction:

Improvepower status recoveryVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent implements feedback by detecting the power status before power failure and using this information to determine the appropriate action after power restoration. The controller reads the stored power status from non-volatile memory and automatically restores the previous state (on or off), preventing wasteful power consumption while maintaining adaptability.

Inventive Principle:

Principle #23Feedback

4Reliability

If an additional microcomputer is used for power control, then power management is improved, but production costs increase greatly

Engineering Contradiction:

Improvepower managementVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies universality by making the existing controller perform multiple functions: it controls the switching circuit unit, manages power status, detects power failures, and restores previous states. This multi-functionality eliminates the need for an additional microcomputer while maintaining reliable power management, thereby reducing production costs.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8862919B2Power control method for image forming apparatus to selectively control switching circuit unit to manage power supply according to last known power status when power is resumed after an abnormal power failure

Publication Date: 2014.10.14 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

An image forming apparatus and a power control method thereof are provided. The image forming apparatus includes: an image forming unit which forms an image; a power supply which supplies operating power for the image forming apparatus; a switching circuit unit which switches to selectively supply the operating power; a memory unit which stores information about power status of the switching circuit unit; and a controller which outputs a power control signal for controlling a switching operation of the switching circuit unit in accordance with the information about the power status stored in the memory unit if power is abnormally shut off and then supplied again from the power supply to the switching circuit unit. With this, the image forming apparatus operates in a last power status, so that power can be prevented from being wastefully consumed or data can be prevented from being lost.