Non-Volatile Memory Spool Buffer Management for Printers
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Solution Overview
Problem
NAND flash memory in printing apparatuses has a limited number of rewriting operations, leading to the generation of defective blocks, which can deplete substitute blocks and cause the memory to become inoperable before reaching the estimated number of printable sheets, due to inadequate detection and management of defective blocks.
Innovation Solution
A management unit is implemented to derive life time consumption rates based on both printed sheets and rewriting operations, controlling the capacity allocated to the spool buffer in non-volatile memory to extend its life and prevent premature failure by restricting writing when life time rates indicate high consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the non-volatile memory is used as a spool buffer for print data, then the printing apparatus can perform secure printing and temporarily store print data, but the limited number of rewriting operations causes defective blocks to generate and deplete substitute blocks, leading to memory inoperability before reaching the estimated number of printable sheets
Solution Approach 1:
The patent applies preliminary action by detecting defective blocks and consuming substitute blocks in advance, before the memory becomes completely inoperable. The control unit performs wear leveling and monitors substitute block consumption proactively, taking corrective actions before the memory reaches its failure threshold, thus preventing premature inoperability while maintaining secure printing functionality
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring the number of defective blocks and substitute block consumption. The control unit detects the state of the non-volatile memory and adjusts its operations accordingly, providing feedback loops that prevent the memory from reaching a critical failure state while maintaining secure printing operations
2Duration of action of stationary object
If wear leveling is conducted to distribute rewriting operations evenly across blocks, then the memory life can be extended, but substitute blocks are consumed faster due to the even distribution of wear, leading to premature memory failure
Solution Approach 1:
The patent applies dynamics by making the wear leveling process adaptive rather than static. The control unit dynamically adjusts the wear leveling strategy based on the current state of defective blocks and substitute block consumption. When substitute blocks are running low, the system modifies its wear leveling behavior to prioritize preserving remaining good blocks, thus extending memory life while preventing premature failure from substitute block depletion
3Quantity of substance
If the capacity allocated to the spool buffer is increased to improve print data storage capability, then more print data can be stored, but the number of rewriting operations increases, accelerating memory degradation and reducing memory life
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the spool buffer capacity allocation based on the memory's current health status. When the memory shows signs of degradation or substitute block consumption increases, the system reduces the spool buffer capacity to minimize rewriting operations. This adaptive parameter adjustment allows the system to maintain adequate print data storage capability while slowing memory degradation and extending memory life
Data Source
AI summary
A printing apparatus includes a non-volatile memory and a management unit that performs management in a case of using the non-volatile memory as a spool buffer for print data. The management unit includes a first derivation unit that derives a first life time consumption rate of the non-volatile memory based on the cumulative number of printed sheets of print media printed with a printing unit, and a second derivation unit that derives a second life time consumption rate of the non-volatile memory based on the number of times of rewriting operations of the non-volatile memory. The management unit controls a capacity allocated to a spool buffer to be defined in the non-volatile memory based on a result of comparison between the second life time consumption rate and the first life time consumption rate.