Dual Developer Image Forming Apparatus for Secure Erasure
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Solution Overview
Problem
Image forming apparatuses using color erasable developers face issues with re-development of images at low temperatures, leading to potential readability of confidential documents even after erasure, compromising security when reused.
Innovation Solution
The apparatus employs a dual supply system for image forming materials, where one developer is erased at a higher temperature and another develops color at a lower temperature, ensuring that confidential documents remain unreadable after erasure by forming specific images with distinct temperature-dependent properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If color erasable developer is cooled to very low temperature after erasure, then the recording medium can be reused, but color development occurs again and confidential information becomes readable
Solution Approach 1:
The invention divides the developer system into two distinct components: a first developer that forms the confidential document image and a second developer that forms a mask image. These two developers have different color development temperature characteristics, allowing them to be controlled independently. The mask image developer remains colorless at low temperatures while the document image developer can be made unreadable, thus preventing unauthorized reading without causing harmful re-development.
Solution Approach 2:
The invention applies different temperature-dependent color development properties to different regions of the recording medium. The first developer (confidential document) and second developer (mask image) are positioned in different locations and exhibit different thermal responses. This local differentiation allows the mask region to remain inactive at low temperatures while the document region maintains its erased state, resolving the security issue.
2Productivity
If heat or light is applied to erase the color of the developer, then the image is erased and recording medium can be reused, but this may cause unintended color development or readability issues
Solution Approach 1:
The invention forms a mask image with a second developer before or during the erasure process. This mask image is designed to prevent color development in specific regions. When heat or light is applied for erasure, the mask image remains stable and prevents unintended color development, ensuring that confidential information remains unreadable even as the recording medium is prepared for reuse.
Solution Approach 2:
The second developer acting as a mask image serves as an intermediary layer between the erasure energy (heat or light) and the first developer containing confidential information. This intermediary absorbs or blocks the erasure energy in critical regions, preventing it from reaching and potentially re-developing the confidential document image, thus maintaining security during the reuse process.
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 approach effectively maintains security by ensuring that confidential documents remain unreadable even when reused, as the stamp image develops color during erasure and the mask image re-develops color at a lower temperature, preventing unintended readability.
Implementation Method 1
a first supply unit configured to supply a first image forming material with a color when an image is formed, and the color of the first image forming material is erased by being heated at a first temperature
Implementation Method 2
a second supply unit configured to supply a second image forming material without a color when an image is formed, and the second image forming material develops the color by being heated at a second temperature lower than the first temperature
Data Source
AI summary
An image forming apparatus forms a stamp image with a stamp image developer having a color developing temperature at a color erasing temperature of an image forming developer, and forms a mask image with a mask image developer having a color re-developing temperature at a temperature not lower than a color re-developing temperature of the image forming developer. Accordingly, when a confidential document is color-erased, the stamp image develops color, and when the color-erased confidential document again develops color, it can not be read.