Safety shield control device
First Claim
Patent Images
1. An interlocking switching system comprising:
- (a) an encoder potted in a generally opaque potting substance and having a pair of terminals and a plurality of reed switches positioned at predetermined locations and connected to form a circuit between said terminals, said plurality of reed switches comprising at least one normally open reed switch and at least one normally closed reed switch;
(b) a decoder potted in a generally opaque potting substance and having a plurality of magnets positioned at locations corresponding to said predetermined locations whereby when said encoder and decoder are brought into proximity with each other, said magnets are operable to form an electrically conductive path having a predetermined impedance between said terminals by closing said at least one normally open reed switch, and by not opening said at least one normally closed reed switch;
(c) a detection circuit wherein said predetermined impedance of said encoder further comprises at least one precision circuit element in said potted circuit to cooperate with said detection circuit; and
,(d) a safety shield associated with said decoder for preventing a user of equipment from accessing potentially hazardous portions of said equipment, and wherein said encoder is associated with a portion of said equipment in juxtaposition with said shield.
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Accused Products
Abstract
An electrical interlock to prevent unauthorized access to potentially hazardous equipment and an associated detection circuit to detect if a safety shield or closure member is open, not securely closed or has been tampered with and to thereupon automatically de-energize the equipment. The detection circuit may comprise a balanced bridge incorporating the electrical interlock into a leg thereof and may also provide a visual or audible indication whenever the bridge is unbalanced thereby indicating an improperly closed safety shield.
38 Citations
13 Claims
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1. An interlocking switching system comprising:
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(a) an encoder potted in a generally opaque potting substance and having a pair of terminals and a plurality of reed switches positioned at predetermined locations and connected to form a circuit between said terminals, said plurality of reed switches comprising at least one normally open reed switch and at least one normally closed reed switch; (b) a decoder potted in a generally opaque potting substance and having a plurality of magnets positioned at locations corresponding to said predetermined locations whereby when said encoder and decoder are brought into proximity with each other, said magnets are operable to form an electrically conductive path having a predetermined impedance between said terminals by closing said at least one normally open reed switch, and by not opening said at least one normally closed reed switch; (c) a detection circuit wherein said predetermined impedance of said encoder further comprises at least one precision circuit element in said potted circuit to cooperate with said detection circuit; and
,(d) a safety shield associated with said decoder for preventing a user of equipment from accessing potentially hazardous portions of said equipment, and wherein said encoder is associated with a portion of said equipment in juxtaposition with said shield. - View Dependent Claims (2, 3)
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4. A detection circuit for equipment having a moveable closure members, said detection circuit providing an indication when at least one of said closure members is not securely closed comprising:
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(a) an associated encoder comprising a plurality of switches and at least one precision resistor; (b) a bridge circuit having four legs, one of said legs comprising said encoder; (c) circuit means to energize said bridge; (d) an indicator to provide an indication whenever said bridge is unbalanced; (e) a decoder carried on said at least one of said closure members and keyed to said encoder; and (f) a balancing adjustment for balancing said bridge circuit in accordance with the number of closures utilized. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification