| 摘要 |
PROBLEM TO BE SOLVED: To prevent a ROM or the like from being illegally exchanged by leaving a trace when a board case is opened. SOLUTION: When locking is performed once in this locking device, a state (b) is attained. When the locking is released, the state (c) is obtained and a green semi-solid solution G flows out from a case body 17. When the locking for the second time is performed in this state, the state (d) is realized and a read semi-solid solution R enters a first tightly sealed tank 25. When the locking is released again in this state, the state (e) is attained and the red semi-solid solution R flows out. That is, since the trace which is the outflow of the semi-solid solution remains when the locking is released in the locking device, it is recognized that the locking has been released. Also, by the color of the semi-solid solution, it is recognized that the locking has been released to the second time.
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