Position detector

A two dimensional position detector comprising:

• first and second members which are moveable relative to each other in first and second directions in a measuring plane;
• said first member comprising a magnetic field generator for generating a magnetic field;
• said second member comprising:
• (i) first and second conductors which are inductively coupled to said magnetic field generator, the first conductor extending in a geometrically varying manner having a first characteristic dimension along said first direction and the second conductor extending in a geometrically varying manner having a second different characteristic dimension along the first direction, as a result of which, in response to a magnetic field generated by said magnetic field generator, a first signal is generated which varies in dependence upon the relative position and orientation of the first conductor and the magnetic field generator and a second different signal is generated which varies in dependence upon the relative position and orientation of the second conductor and the magnetic field generator;
• and
• (ii) third and fourth conductors which are inductively coupled to said magnetic field generator, the third conductor extending in a geometrically varying manner having a third characteristic dimension along said second direction and the fourth conductor extending in a geometrically varying manner having a fourth characteristic dimension along said second direction different from said third characteristic dimension, as a result of which, in response to a magnetic field generated by said magnetic field generator, a third signal is generated which varies in dependence upon the relative position and orientation of the third conductor and the magnetic field generator and a fourth different signal is generated which varies in dependence upon the relative position and orientation of the fourth conductor and the magnetic field generator;
• means for processing said first and second signals to determine the relative position and orientation of the two moveable members in said first direction using a relationship between the respective characteristic dimension of the geometrical variation of said first and second conductors;
• means for processing said third and fourth signals to determine the relative position and orientation of the two moveable members along said second direction using a relationship between the respective characteristic dimension of the geometrical variation of said third and fourth conductors;
• and
• means for combining the relative orientations in said first and second directions to determine the relative orientation of said first and second members in said measuring plane.

A position detector comprising:

• first and second members which are moveable relative to each other in a measuring plane;
• said first member comprising a magnetic field generator for generating a magnetic field;
• said second member comprising first and second groups of circuits for sensing the relative position and orientation of the first and second members in two different directions in said plane;
• and
• means for determining the relative orientation of the first and second members in said plane using the relative orientations in said first and second directions;
• characterized in that each of groups of circuits comprises first and second conductors which are inductively coupled to said magnetic field generator, the first conductor extending in a geometrically varying manner having a first characteristic dimension along the corresponding direction and the second conductor extending in a geometrically varying manner having a second different characteristic dimension along said corresponding direction.

A position detector comprising:

• first and second members which are moveable relative to each other along a measuring path;
• said first member comprising a magnetic field generator for generating a magnetic field;
• said second member comprising first and second circuits each comprising a conductor which is inductively coupled to said magnetic field generator, the conductor of said first circuit extending in a geometrically varying manner having a first characteristic dimension along the measuring path and the conductor of said second circuit extending in a geometrically varying manner having a second different characteristic dimension along the measuring path, as a result of which, in response to a magnetic field generated by said magnetic field generator, a first signal is generated in said first circuit and second different signal is generated in said second circuit, the first and second signals both varying in dependence upon the relative position and orientation of the two moveable members;
• and
• means for processing said first and second signals to determine said relative position and orientation of said first and second members using a relationship between the respective characteristics dimension of the geometrical variation of said two conductors.

A position detector comprising

• first and second members which are moveable relative to each other along a measuring path;
• said first member comprising a magnetic field generator for generating a magnetic field;
• said second member comprising first and second periodic windings which extend along the measuring path and which are inductively coupled to said magnetic field generator, the period of said first winding being different to the period of said second winding, as a result of which, in response to a magnetic field generated by said magnetic field generator, a first signal is generated in said first circuit and a second different signal is generated in said second circuit, the first and second signals both varying in a substantially sinusoidal manner in dependence upon the relative position and orientation of the two moveable members;
• means for processing said first and second signals to provide a first value which depends upon said relative position and orientation and a second different value which depends upon said relative position and orientation;
• and
• means for combining said first and second values to determine said relative position and orientation in dependence upon a relationship between the two periods of said windings.

An x-y digitizing system comprising:

• first and second members that are moveable relative to each other in the x-y direction;
• said first member comprising a first magnetic field generator for generating a magnetic field substantially in a first direction and a second magnetic field generator for generating a magnetic field substantially in a second direction different from said first direction;
• said second member comprising two sets of periodic windings, each set comprising first and second periodic windings, which extend along the measuring path and which are inductively coupled to said first and second magnetic field generators, the period of said first winding being different to the period of said second winding, as a result of which, in response to a magnetic field generated by each of said magnetic field generators, a first signal is generated in said first circuit and a second different signal is generated in said second circuit, the first and second signals both varying in dependence upon the relative position and orientation of the two moveable members;
• means for processing said first and second signals from each of said magnetic field generators to provide a first value which depends upon said relative position and orientation and a second different value which depends upon said relative position and orientation;
• and
• means for combining said first and second values to determine said relative x-y position and to determine said relative orientation in dependence upon a relationship between the two periods of said windings.

A method of detecting the relative position and orientation between first and second members that are moveable relative to each other along a measuring path, the method comprising the steps of:

• providing a magnetic field generator for generating a magnetic field on said first member;
• providing first and second conductors which are inductively coupled to said magnetic field generator on said second member, the first conductor extending in a geometrically varying manner having a first characteristic dimension along the measuring path and the second conductor extending in a geometrically varying manner having a second different characteristic dimension along the measuring path, as a result of which, in response to a magnetic field generated by said magnetic field generator, a first signal is generated which varies in dependence upon the relative position and orientation of the first conductor and the magnetic field generator and a second different signal is generated which varies in dependence upon the relative position and orientation of the second conductor and the magnetic field generator;
• generating a magnetic field using said magnetic field generator;
• receiving the first and second signals generated in response to the generation of said magnetic field by said magnetic field generator;
• and
• processing said first and second signals to determine the relative position and orientation of the two moveable members using a relationship between the respective characteristic dimension of the geometrical variation of said two conductors.