Absolute digital position measurement system

In a linear position measurement system comprising a linear member having a length many times as great as its width, said linear member including at least one serpentine conductive element extending substantially the length of the linear member, an interacting movable member, and readout means electrically connected to said linear member for providing an indication of the position of the movable member along the linear member, the improvement comprising:

• a. inductor means extending substantially the entire length of said linear member,
• b. inductive means for transmitting first electrical signals from said movable member to said serpentine conductive element and for transmitting second electrical signals from said inductor means to said movable member,
• c. signal generating means for generating said second electrical signals in said inductor means, and
• d. means for separating said first signals from said second signals.

In a linear position measurement system comprising a linear member having a length many times as great as its width, a longitudinally movable member coupled with the linear member, and readout means connected to the linear member for indicating the position of the movable member along the linear member, the improvement comprising:

• a. means carried by said movable member for applying first signals in the form of an alternating magnetic field to said linear member in a limited longitudinal portion of said linear member,
• b. a plurality of electrical conductors extending lengthwise of and carried by said linear member, each of said conductors being electrically connected to said readout means, each of said conductors including at least one first longitudinally extending reach and one second longitudinally extending reach, displaced longitudinally from said first reach,
• i. each said first reach being positioned to cause a Phase a signal to be induced in said conductor when said movable member is longitudinally adjacent said first reach,
• ii. each said second reach being positioned to cause a phase B signal to be induced in said conductor when said movable member is longitudinally adjacent said second reach, said Phase B signal not being in phase with said Phase A signal, and
• c. phase comparing means in said readout means for distinguishing between said Phase A and Phase B signals in said conductors.

A linear position measurement system comprising a linear member having a length many times as great as its width;

• a longitudinally movable element cooperative with the linear member;
• and readout means for indicating the position of the movable element with respect to the linear member, said linear member being divided into a plurality m of discrete linear positions along its length, said linear member comprising n coded conductors extending lengthwise of the linear member, the number of linear positions m being at least several times as great as the number of conductors n, each conductor representing one place of an n-place binary code and being operatively connected to said readout means, each conductor comprising along the length of the linear member alternating first longitudinally extending portions cooperating with said movable element to produce in said readout means a signal representative of a logical 1 when said movable element is longitudinally adjacent one of said first portions and second longitudinally extending portions which produce in said readout means a signal representative of a logical 0 when said movable element is longitudinally adjacent one of said second portions, said conductors being so arranged that when said movable member is longitudinally adjacent any one of said m linear positions of said linear member said first and second portions of said conductors at that linear position produce in said readout means a unique code word representative of that linear position.

A linear position measurement system comprising a linear member having a length many times as great as its width;

• a longitudinally movable element cooperative with the linear member;
• and readout means for indicating the position of the movable element with respect to the linear member, said linear member being divided into a plurality m of discrete linear positions along its length, said linear member comprising n coded conductors extending lengthwise of the linear member, the number of linear positions m being at least several times as great as the number of conductors n, each conductor representing one place of an n-place binary code and being operatively connected to said readout means, each conductor comprising along the length of the linear member alternating first longitudinally extending portions which couple with said movable element to produce in said readout means a signal representative of a logical 1 when said movable element is longitudinally adjacent one of said first portions and second longitudinally extending portions which couple with said movable element to produce in said readout means a signal representative of a logical 0 when said movable element is longitudinally adjacent one of said second portions, said first and second portions of said conductors being arranged to form a unique binary code word at each of said m linear positions along the length of said linear member.

A linear position measurement system comprising a linear member having a length many times as great as its width;

• a longitudinally movable element cooperative with the linear member;
• and readout means for indicating the position of the movable element with respect to the linear member, said linear member being divided into a plurality m of discrete linear positions along its length, said linear member comprising:
• n coded conductors extending lengthwise of the linear member, each conductor representing one place of an n-place permutated digital code of base b, n being greater than b and m being at least several times greater than n, each conductor being operatively connected to said readout means, each conductor comprising a plurality of conductively joined longitudinally extending portions, each said longitudinally extending portion being constructed and arranged to couple with said movable element when said movable element is longitudinally adjacent said portion to produce in said readout means signals representative of one of the b digits of said code;
• said portions being so arranged that when said movable member is longitudinally adjacent any one of said m linear positions of said linear member said portions of said conductors produce in said readout means a unique code word representative of that linear position.

A linear position measurement system comprising a linear member having a length many times as great as its width, said linear member being divided into a plurality m of discrete linear positions along its length;

• a longitudinally movable element cooperative with the linear member;
• readout means for indicating the position of the movable element with respect to the linear member, means for producing an alternating magnetic field along substantially the entire length of said linear member, and n coded conductors carried by the linear member, the number of linear positions m being at least several times as great as the number of conductors n, each conductor representing one place of an n-place permutated digital code and being operatively connected to said readout means,
• said movable element, at all m linear positions of said linear member, inductively coupling said alternating magnetic field and applying to said coded conductors signals which are read as a code word by said readout means,
• said conductors being so constructed and arranged that said movable element produces in said readout means a unique digital code word for each of said m positions.