Electricity: measuring and testing – Electrical speed measuring
Patent
1996-10-07
1998-08-11
Snow, Walter E.
Electricity: measuring and testing
Electrical speed measuring
340648, G01P 1300
Patent
active
057931976
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an apparatus that confirms that a movable portion has stopped and, to be more specific, it relates to an apparatus that detects that the speed of a movable portion is at or below a specific value and outputs its detection signal as a movable portion stopped signal.
BACKGROUND ART
In an apparatus that includes a movable portion driven by a motor or the like, i.e., a robot or the like, a safety device that allows the operator to approach the apparatus only after it has been detected that the movable portion has completely stopped operation is required in order to assure 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 the motor 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., one; a delay that is generated in issuing notification of the stop because the device is not provided with a function for detecting the rotation rate and two; since a bridge circuit is employed for the rotation sensor, adjustment of the bridge circuit is required.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide an apparatus for confirming stop of movable portion with which the delay in issuing notification of the stop of the movable portion is reduced.
It is a further object of the present invention to provide an apparatus for confirming stop of movable portion that is capable of issuing notification of movable portion stop after detecting that a coil is combined with the movable portion correctly, so that a danger state, in which the coil may come in contact with the movable portion, cannot occur.
It is a further object of the present invention to provide an apparatus for confirming stop of movable portion in which notification of movable portion stop is issued based upon verification that the movable portion has been monitored until immediately before the issuance of such notification.
It is a still further object of the present invention to provide an apparatus for confirming stop of movable portion that is capable of generating a signal at the time of startup to indicate stop of the movable portion based upon verification made via a startup switch.
It is a still further object of the present invention to provide an apparatus for confirming stop of movable portion that issues notification of movable portion stop based upon verification that the movable portion has been monitored, even at the time of startup.
It is a still further object of the present invention to provide an apparatus for confirming stop of movable portion that is capable of reducing the delay time that elapses before the movable portion stopped signal ceases when the movable portion has started to rotate or move.
It is a still further object of the present invention to provide an apparatus for confirming stop of movable portion that facilitates adjustment.
In order to achieve the objects described above, the apparatus for confirming stop of movable portion according to the present invention comprises a detection means, a speed judgement circuit, a level detection circuit and an AND circuit.
The detection means includes a coil that is provided in close proximity to a surface of the movable portion to detect changes in impedance at the coil caused by indentations and projections provided at the surface of the movable portion and to generate a detection signal therefrom. The detection signal output from the detection means is provided to the speed judgement circuit and when the detection signal change interval becomes greater than specific length of time, the speed judgement circuit generates a sustained high level output signal. The detection signal output from the detection means is also provid
Anzai Hiroji
Futsuhara Koichi
Shirai Toshihito
Snow Walter E.
The Nippon Signal Co. Ltd.
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