| 摘要 |
PURPOSE:To prevent an erroneous input from a specific key perfectly by making the specific key ineffective and effective by operating a series of >=2 keys successively. CONSTITUTION:On an electronic desk-top calculator provided with a stopwatch function, etc., when a stopwatch starting and stopping key 6 is to be locked for preventing malfunction in stopwatch operation, a key word is inputted by using an input key 3 and then a locking key 8 is pushed, then a lock signal for the key word in stored in a register 14 via an arithmetic part 10. The register 14, when any number other than 0 is inputted, sends a signal to a locking flip-flop 16, which is set. The output Q' of this flip-flop 16 comes to 0 and the starting and stopping key 6 is made ineffective and locked. In this state, when a clear key 9 is pushed and then an access key 7 is pushed, the counting state of the stopwatch is displayed on a display device 2. |
