Memory Control Interface for Illegal Access Detection
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Solution Overview
Problem
Image forming apparatuses with nonvolatile memory are vulnerable to illegal access and rewriting through signal wires, which can disrupt normal operations and affect print quality by allowing unauthorized usage of consumable items.
Innovation Solution
A memory control device with an interface that uses a predetermined communication regulation, an illegal access detection mechanism, and a signal control part to switch the interface from a write-allowed to a write-inhibited state when illegal access is detected, preventing unauthorized rewriting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If nonvolatile memory is built in the image forming apparatus to store setting information and management information, then the apparatus can manage its status and perform various processes, but the wiring to control nonvolatile memory can be illegally accessed to rewrite information stored in the memory
Solution Approach 1:
The patent introduces an interface circuit as an intermediary between the memory control unit and the nonvolatile memory. This interface circuit includes a signal line that is controlled by both the memory control unit and an external control unit, creating a mediator that prevents direct illegal access to the memory while still allowing legitimate write operations to proceed normally.
2Ease of operation
If the interface part is made writable to allow normal memory operations, then the apparatus can perform regular processes, but illegal rewriting of information can occur through added wiring to signal wires
Solution Approach 1:
The patent implements preliminary anti-action by having the interface circuit continuously monitor the signal state before write operations occur. The external control unit detects illegal access attempts through the controlled signal line and preemptively prevents them by blocking the write signal, thereby counteracting harmful factors before they can affect the memory.
Solution Approach 2:
The patent establishes a feedback mechanism where the interface circuit monitors the signal state from the memory control unit and provides this information to the external control unit. Based on this feedback, the external control unit can detect illegal access patterns and respond by inhibiting write operations, creating a closed-loop protection system.
3Reliability
If setting information and management information are stored in nonvolatile memory, then the apparatus can manage consumable items and restrict usage, but illegal rewriting can cause consumable items other than regular ones to become usable, declining print quality
Solution Approach 1:
The interface circuit serves as a mediator that protects the management information in nonvolatile memory from illegal rewriting. By controlling the signal line through both the memory control unit and external control unit, it ensures that only authorized write operations can modify the usage restriction data, thereby preventing unauthorized consumable items from being enabled while maintaining proper usage management.
Data Source
AI summary
A memory control device includes a memory control part that controls memory through an interface part in accordance with a predetermined communication regulation, an illegal access detection part that detects an illegal access to the memory according to an access state from the memory control part to the memory and a signal state of the interface part, and a signal control part that switches the signal state of the interface part from a write-allowed state, in which the interface part is able to be written, to a write-inhibited state, in which the interface part is protected from being rewritten, when the illegal access is detected by the illegal access detection part.