| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent device failure due to degradation in advance by automatically regularly determining a degradation state of a nonvolatile memory built-in an apparatus in practical use to judge whether continuous use is allowable.SOLUTION: When characteristic deterioration progresses, a memory cell is not completely charged during writing and charged electrical charges are easily released. Then, a threshold voltage determining a logical value 1/0 becomes low and output data becomes unstable, soon being inverted. Before data is inverted due to deterioration, a point is detected where the logical value 1/0 of the output data is inverted when an applied voltage (a read-out voltage) is changed, and a degradation state is determined by the change.</p> |
