Method and apparatus for assuring safe work
AssigneeThe Nippon Signal Co., Ltd.
InventorsMasao Mukaidono, Noboru Sugimoto, Koichi Futsuhara
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Abstract
A method for assuring a safe work space operates so that a work enable signal is generated only when absence of workers from the work space where the workers work in cooperation with a machine is detected. The work enable signal has a logical value of 1 corresponding to a high energy state and only this signal can initiate activation of the machine sharing the subject work space thereby assuring safe environments for workers.
Claims9
A safe work assuring method for assuring safety of a worker in work space where the worker works in cooperation with a machine, comprising steps of:
- detecting a safe status of the worker by receiving an AC input signal at a high level;
- detecting a dangerous status of the worker by receiving the AC input signal at a low level including zero;
- generating an output signal at a logical value of 1, indicative of the safe status and corresponding to a high energy status, upon reception of the AC input signal at the high level;
- generating said output signal at a logical value of 0, indicative of the dangerous status and corresponding to a low energy status, upon reception of the AC input signal at the low level including zero;
- detecting the safe and dangerous status of the worker by using a sensor in which a sensor output signal is extinguished when the sensor fails, and a logical value of 0 is indicated, irrespective of the level of the AC input signal received thereby;
- performing a logical product calculation of the sensor output signal, wherein a logical value of 1 is indicative of a safe status of the sensor, and a work enable signal of a logical value of 1 on a machine side, by using a logical product element having a logical output signal which cannot erroneously come to a logical value of 1;
- and
- generating a work executing energy for the work space on the machine side on the basis of the logical product calculation.
A safe work assuring apparatus for assuring safety of a worker in work space where the worker works in cooperation with a machine, comprising:
- a sensor for detecting a safe status of the worker by receiving an AC input signal at a high level, detecting a dangerous status of the worker by receiving the AC input signal at a low level including zero, amplifying and rectifying an AC signal based on the AC input signal, generating a rectified output signal indicative of the safe status as a logical value of 1 upon reception of the AC input signal at the high level, generating a rectified output signal indicative of the dangerous status as a logical value of 0 upon reception of the AC input signal at the lower level including zero, and making the rectified output signal come to a logical value of 0 when the sensor fails;
- and
- a logical product element having two input signals, in which the rectified output signal of the sensor is one input signal, a work enabling signal on the machine is the other input signal and the rectified output signal comes to a logical value of 0 when the logical product element fails, an output signal of the logical product element being a drive signal for generating work executing energy on a movable section of the machine.
Dependencies are inferred from the claim text.