Linear motion screened inductance sensors
First Claim
1. A sensing system comprising a drive or exciting winding for establishing a forward or drive field at least one secondary or sense winding in which a voltage may be induced in the presence of said forward or drive field, and at least one conductive screen within which eddy currents are generated in the presence of said forward or drive field to establish a counter-field opposing said forward or drive field, said drive or exciting winding and said at least one secondary or sense winding being accommodated in a displaceable sensor portion and said at least one conductive screen being fixedly located relative to said displaceable sensor portion, said secondary or sense winding being shaded to a varying extent by said at least one conductive screen when said displaceable sensor portion is in the vicinity of said at least one conductive screen to thereby vary the voltage induced in said at least one secondary or sense winding and said at least one secondary or sense winding being oriented to provide a varying voltage output substantially indicative of the position of said displaceable sensor portion relative to said at least one conductive screen in a single direction of relative displacement of said displaceable sensor portion and said at least one conductive screen, said drive or exciting winding being configured so that in the absence of said at least one conductive screen said forward or drive field is substantially even over said at least one secondary or sense winding in said single direction of relative displacement of said displaceable sensor portion and said at least one conductive screen, said at least one secondary or sense winding being a two-terminal winding, and said at least one conductive screen defining a plane which is substantially parallel to a notional surface defined by said at least one secondary or sense winding.
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Accused Products
Abstract
In a screened inductance sensor system having a drive winding energizable to set up an alternating magnetic drive field, a sense winding links the drive field and a screening element modulates the spatial distribution of the drive field, when in the vicinity of the sense winding. Variations in voltage induced in the sense winding provide an indication of the relative position of the screening element and the sense winding. The drive winding and the sense winding are accommodated in a displaceable portion of the sensor, and the screening element is fixedly located relative to the movable sensor portion. Modulation of the spatial distribution of the drive field occurs when the displaceable sensor portion is moved into the vicinity of the screening element. In application of the system to control of vehicles following a predetermined path, fixed screening elements may be located at spaced apart intervals along the path, where the vehicles are on tracks, to provide locational signals according as the vehicles pass these fixed screens. The system may also be applied to providing guidance and position information for a steerable vehicle, in which case two sense windings are used, one responsive to sidewise deviation from the intended path of travel, and the other sense winding providing a cycled output signal, which is counted to yield a measure of distance travelled.
56 Citations
22 Claims
- 1. A sensing system comprising a drive or exciting winding for establishing a forward or drive field at least one secondary or sense winding in which a voltage may be induced in the presence of said forward or drive field, and at least one conductive screen within which eddy currents are generated in the presence of said forward or drive field to establish a counter-field opposing said forward or drive field, said drive or exciting winding and said at least one secondary or sense winding being accommodated in a displaceable sensor portion and said at least one conductive screen being fixedly located relative to said displaceable sensor portion, said secondary or sense winding being shaded to a varying extent by said at least one conductive screen when said displaceable sensor portion is in the vicinity of said at least one conductive screen to thereby vary the voltage induced in said at least one secondary or sense winding and said at least one secondary or sense winding being oriented to provide a varying voltage output substantially indicative of the position of said displaceable sensor portion relative to said at least one conductive screen in a single direction of relative displacement of said displaceable sensor portion and said at least one conductive screen, said drive or exciting winding being configured so that in the absence of said at least one conductive screen said forward or drive field is substantially even over said at least one secondary or sense winding in said single direction of relative displacement of said displaceable sensor portion and said at least one conductive screen, said at least one secondary or sense winding being a two-terminal winding, and said at least one conductive screen defining a plane which is substantially parallel to a notional surface defined by said at least one secondary or sense winding.
- 8. A position sensing system for tracked vehicles comprising a drive or exciting winding for establishing a forward or drive field, at least one secondary or sense winding in which a voltage may be induced in the presence of said forward or drive field, and at least one conductive screen within which eddy currents are generated in the presence of said forward or drive field to establish a counter-field opposing said forward or drive field, said drive or exciting winding and said at least one secondary or sense winding being accommodated in a displaceable sensor portion attachable to a tracked vehicle and said at least one conductive screen being aligned with the intended path of movement of the tracked vehicle said secondary or sense winding being shaded to a varying extent by said at least one conductive screen when said displaceable sensor portion is moved into the vicinity of said at least one conductive screen to thereby vary the voltage induced in said at least one secondary or sense winding and said at least one secondary or sense winding being oriented to provide a voltage output indicative of the presence of said displaceable sensor portion in the vicinity of said at least one conductive screen, said drive or exciting winding being configured so that in the absence of said at least one conductive screen said forward or drive field is substantially even over said at least one secondary or sense winding in the direction of travel of said tracked vehicle, said at least one secondary or sense winding being a two-terminal winding, and said at least one conductive screen having a surface region which is substantially parallel to a notional surface defined by said at least one secondary or sense winding.
- 11. A guidance system for steerable vehicles comprising a drive or exciting winding for establishing a forward or drive field, at least one secondary or sense winding in which a voltage may be induced in the presence of said forward or drive field, and at least one conductive screen within which eddy currents are generated in the presence of said forward or drive field to establish a counter-field opposing said forward or drive field, said drive or exciting winding and said at least one secondary or sense winding being accommodated in a displaceable sensor portion attachable to a vehicle to be guided by the system and said at least one conductive screen being aligned with an intended path of movement of said vehicle said secondary or sense winding being shaded to a varying extent by said at least one conductive screen when said displaceable sensor portion is in the vicinity of said at least one conductive screen to thereby vary the voltage induced in said at least one secondary or sense winding and said at least one secondary or sense winding being oriented to provide a varying voltage output substantially indicative of the position of said displaceable sensor portion relative to said at least one conductive screen in a single direction of relative displacement of said displaceable sensor portion and said at least one conductive screen, said drive or exciting winding being configured so that in the absence of said at least one conductive screen said forward or drive field is substantially even over said at least one secondary or sense winding in said single direction of relative displacement of said displaceable sensor portion and said at least one conductive screen, said at least one secondary or sense winding being a two-terminal winding, and said at least one conductive screen defining a plane which is substantially parallel to a notional surface defined by said at least one secondary or sense winding.
- 20. A sensing system comprising a drive or exciting winding for establishing a forward or drive field, two secondary or sense windings in each of which a voltage may be induced in the presence of said forward or drive field, and two series of conductive screens, eddy currents being generated in said conductive screens in the presence of said forward or drive field to establish a counter-field opposing said forward or drive field, said drive or exciting winding and said two secondary or sense windings being accommodated in a displaceable sensor portion and said two series of conductive screens being fixedly located relative to said displaceable sensor portion, each of said secondary or sense windings being shaded to a varying extent by a conductive screen of a respective one of said two series of conductive screens when said displaceable sensor portion is moved into the vicinity of said conductive screen to thereby vary the voltage induced in said secondary or sense winding and each of said two secondary or sense windings being oriented to provide a varying voltage output substantially indicative of the position of said displaceable sensor portion relative to said two series of conductive screens in a single direction of relative displacement of said displaceable sensor portion and said two series of conductive screens, said drive or exciting winding being configured so that in the absence of said conductive screens, said forward or drive field is substantially even over said two secondary or sense windings in said single direction of relative displacement of said displaceable sensor portion and said two series of conductive screens, each of said two secondary or sense windings being a two-terminal winding, each of said conductive screens having a surface region which is substantially parallel to a notional surface defined by said two secondary or sense windings, and the number of conductive screens of one of said series of conductive screens differing from the number of conductive screens of the other of said series of conductive screens.
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22. A screened inductance sensor system comprising a drive or exciting winding for establishing a forward or drive field, means for energising the drive winding to set up an alternating magnetic field, at least one secondary or sense winding in which a voltage may be induced in the presence of said forward or drive field, at least one conductive screen within which eddy currents are generated in the presence of said forward or drive field to establish a counter-field opposing said forward or drive field, said drive or exciting winding and said at least one secondary or sense winding being accommodated in a displaceable sensor portion and said at least one conductive screen being fixedly located relative to said displaceable sensor portion, said secondary or sense winding being shaded to a varying extent by said at least one conductive screen when said displaceable sensor portion is in the vicinity of said at least one conductive screen to thereby vary the voltage induced in said at least one secondary or sense winding and said at least one secondary or sense winding being oriented to provide a varying voltage output substantially indicative of the position of said displaceable sensor portion relative to said at least one conductive screen in a single direction of relative displacement of said displaceable sensor portion and said at least one conductive screen, said drive or exciting winding being configured so that in the absence of said at least one conductive screen said forward or drive field is substantially even over said at least one secondary or sense winding in said single direction of relative displacement of said at least one displaceable sensor portion and said at least one conductive screen, said at least one secondary or sense winding being a two-terminal winding, said at least one conductive screen defining a plane which is substantially parallel to a notional surface defined by said at least one secondary or sense winding, and the system comprising means for measuring said varying voltage output of said at least one secondary or sense winding to provide at least an indication of the relative position of the displaceable sensor portion and said at least one conductive screen.
Specification