Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1996-10-07
1999-01-19
Hofsass, Jeffery A.
Communications: electrical
Condition responsive indicating system
Specific condition
340635, 340679, 318450, G08B 2100
Patent
active
058618139
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a safety securing device that allows an operator to approach a mechanical movable portion after the mechanical movable portion, which is driven by a motor M or the like, has stopped rotating or moving. The safety securing device according to the present invention is particularly suited for constituting a guard system in which the mechanical movable portion is surrounded by a fence with a door provided with a locking device at a portion of the fence such that, when the locking device of the door is released, the mechanical movable portion within the fence can be approached.
BACKGROUND ART
A safety securing device of this type is disclosed in PCT/JP93/00758. Also, a sensor for verifying that the rotation or movement of a mechanical movable portion has stopped is disclosed in International Publication WO94/23303. In addition, a device for detecting that rotation is at a specific rate or lower is also required in an apparatus that includes a mechanical movable portion driven by a motor M or the like, i.e., a robot or the like, as a safety device that allows the operator to approach the apparatus only after the mechanical movable portion has completely stopped its operation, in order to assure the safety of the operator who must approach the apparatus. Such safety devices include the motor rotation stop detecting device disclosed in International Publication WO94/23303, which is capable of reliably detecting that the rotation of a motor M has stopped, including rotation under inertia, and operates toward safety when the apparatus has had a failure, thereby providing a high degree of safety. However, the device disclosed in this prior art publication has two problems yet to be solved, i.e., a delay in issuing notification of the stop that occurs because the device is not provided with a function for detecting the rotation rate and, since a bridge circuit is employed for a rotation sensor, adjustment of the bridge circuit is required.
These problems are eliminated in PCT/JP95/00165 for which an application was submitted by the applicant. However, PCT/JP95/00165 only discloses the technology for issuing notification of mechanical movable portion stop, and the disclosure does not encompass the use of the mechanical movable portion stop signal as a signal for assuring safety of an operator against the mechanical movable portion.
DISCLOSURE OF THE INVENTION
Accordingly, it is an object of the present invention to provide a safety securing device that assures the safety of an operator by using a mechanical movable portion stop signal and a mechanical movable portion rotation signal as signals for assuring the safety of the operator against the mechanical movable portion.
It is a further object of the present invention to provide a safety securing device that assures the safety of the operator by using a mechanical movable portion stop signal and a mechanical movable portion rotation signal as signals for assuring the safety of the operator against the mechanical movable portion when constituting a guard system in which the mechanical movable portion is enclosed by a fence such that, at a portion thereof, a door having a locking device is provided and the mechanical movable portion within the fence can be approached when the locking device of the door is released.
The operation of the mechanical movable portion may include two modes, i.e., rotatory and linear movement. In this specification, in order to simplify the explanation, it is assumed that the operation is rotatory, and that the explanation includes linear movement.
In order to achieve the objects described above, the safety securing device according to the present invention includes a rotation detecting means, a rotation monitoring circuit, a rotation stop monitoring circuit and a movable portion control circuit.
The rotation detecting means detects rotation of the mechanical movable portion and outputs a detection signal that corresponds to the rotation rate. The rotation monitoring circuit, to which the
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Hofsass Jeffery A.
The Nippon Signal Co. Ltd.
Trieu Van T.
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