| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem in the conventional apparatus by considerably simplifying a monitor/control device, that is, a safety device to provide a resolution method for reducing the risk of malfunction of a system economically. SOLUTION: According to the invention, a signal Se outputted by a resistance analog sensor 2 in the safety device is surely processed, and the signal Se is converted to a digital signal n in an analog-digital converter 4 for resolution R. The digital signal n1 is acquired and stored, and then the supply voltage (Va, Vb) of the sensor 2 is inverted (in an inverting circuit 8) to acquire a new digital signal n2. Two signals (n1, n2) are added, and the sum S of them is compared with the resolution R of the converter 4. A control signal Cm of an actuator 6 corresponding to a preset Sc is valid or invalid depending on whether the sum S is equal to the resolution R or not. This invention is applied to the safety device of a tower crane.
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