Erasable Ink Image Overwriting for Confidentiality Security

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Solution Overview

Problem

Inkjet printing systems that reuse sheets with erasable ink face issues where confidential information can reappear when sheets are cooled, compromising security due to recombination of pigment and developer at lower temperatures.

Innovation Solution

An image forming apparatus and method that includes a mark detection system to identify confidential information, followed by overwriting with a pattern to prevent recognition of the image, using erasable ink to ensure confidentiality by maintaining the ink in a decolorized state across temperature variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If erasable ink is used for sheet reuse, then the sheet can be erased and reused, but the confidential information may reappear when the sheet is cooled

Engineering Contradiction:

Improvesheet reuse capabilityVSAvoidconfidentiality security

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by overwriting confidential information with a meaningless pattern before the sheet is cooled. This preemptive measure ensures that even if the erasable ink properties change with temperature, the original confidential content cannot be recovered because it has already been covered with random data.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful temperature-dependent recombination of pigment and developer into a beneficial security feature. By overwriting with a pattern at a specific temperature state and then cooling the sheet, the system ensures that any potential reappearance of original content is masked by the overwritten pattern, turning the temperature sensitivity into an additional security layer.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Ease of operation

If the pigment and developer are separated by heating, then the image is erased, but they recombine when cooled causing the image to reappear

Engineering Contradiction:

Improveerasing functionVSAvoidconfidential information leakage

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The patent converts the harmful recombination phenomenon into a beneficial security mechanism. By overwriting with a meaningless pattern after heating separation but before cooling recombination, the system ensures that when the pigment and developer recombine, they form the overwritten pattern rather than the original confidential information, thus preventing leakage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system performs the overwrite operation as a preliminary action between the heating separation and cooling recombination phases. This timing ensures that the confidential information is masked before the recombination process occurs, preventing any potential information leakage while maintaining the ease of erasing operation.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If a mark detection system and overwriting portion are added, then confidentiality is improved, but the device complexity increases

Engineering Contradiction:

Improveconfidentiality securityVSAvoidsystem structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies universality by making the image forming apparatus perform multiple functions: it can detect marks indicating confidential information, overwrite with patterns, and cool sheets. By integrating these functions into the existing image forming system, the patent minimizes additional complexity while achieving enhanced confidentiality security.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Prevents the re-emergence of confidential information, maintaining security by ensuring that erased images remain indecipherable even if the sheet is cooled, thus enhancing confidentiality in reused prints.

Implementation Method 1

an inkjet printer and so on are proposed which prints an ink including the leuco dye by an inkjet apparatus and erases using a thermal bar or a thermal head

Methodology Applied

Scientific EffectThermal heating: Heating

Implementation Method 2

an ink is disclosed which exhibits colors by the chemical combination of the coloring substance and the developer at a normal temperature equal to or lower than 40° C., the chemical combination breaks down at a temperature equal to or larger than 100° C.

Methodology Applied

Scientific EffectThermal decomposition: Decomposition (biological)

Data Source

PatentUS8308262B2Image forming apparatus and image forming method

Publication Date: 2012.11.13 KK TOSHIBA

AI summary

An image forming apparatus includes an image forming portion to form an image on a sheet using an erasable ink, a sheet supply tray to load the sheet on which the image was formed using the erasable ink, a mark detecting portion to detect a mark indicating that the image formed on the sheet conveyed from the sheet supply tray includes a confidential information, and an overwriting portion to overwrite so as not to make recognizable the image of at least an area including the confidential information out of the image formed on the sheet, in case that the mark is detected by the mark detecting portion.