Safety system for machinery
A safety system for a machine having a danger zone includes an induction coil having one or more turns extending along the periphery of a part of a worker's body as, for example, extending alone the fingers of a glove worn by the worker. A drive circuit applies a time-varying current having an identifiable characteristic such as the frequency of an alternating current. A magnetic field having the characteristic of the time-varying current is induced in an omnidirectional magnetic field sensor mounted adjacent the danger zone. The magnitude of this field is monitored. When the magnitude exceeds a threshold, a warning signal is issued and protective action may be taken, such as stopping or reversing the machine.
1. An element for use in a safety system comprising:
(a) a support including a body region adapted to overlie at least a portion of a palm or back of a human hand and one or more elongated digit regions projecting from a base adjacent the body region to a tip remote from the body region, each digit region being adapted to overlie a digit of the hand when the body region overlies the palm or back of the hand;
(b) an induction coil comprising one or more continuous conductive wires, each continuous conductive wire including one or more segments formed in a plurality of overlapping loops having a winding number of two or greater, each loop of the segment including a pair of elongated runs continuously extending from the base of one said digit region to the tip of that digit region and a bend adjacent the tip of that digit region; and
(c) a drive circuit coupled to the induction coil and configured to apply a time-varying current to the induction coil.
2. An element as claimed in claim 1 wherein the support is in the form of a glove.
3. An element as claimed in claim 1 wherein the plurality of overlapping loops of at least one segment of the continuous conductive wire extends along a periphery of the body region.
4. An element as claimed in claim 1 further comprising a battery configured to power the drive circuit.
5. An element as claimed in claim 4 wherein the battery and the drive circuit are mounted on the support.
6. An element as claimed in claim 1 , wherein the induction coil includes a plurality of continuous conductive wires in parallel with one another, wherein the respective pluralities of overlapping loops of the plurality of continuous conductive wires are positioned in different respective digit regions of the support.
7. An element as claimed in claim 1 , wherein the induction coil comprises one continuous conductive wire including a plurality of wire segments connected in series to one another, each wire segment including a respective plurality of overlapping loops positioned in a different respective digit region of the support.
8. An element as claimed in claim 7 wherein the support is in the form of a glove.
9. An element as claimed in claim 7 wherein the plurality of overlapping loops of at least one segment of the continuous conductive wire extends along a periphery of the body region.
10. An element as claimed in claim 7 , wherein the support includes five elongated digit regions, and wherein the continuous conductive wire includes five wire segments, each wire segment including a respective plurality of overlapping loops positioned in a different respective digit region of the support.