INCREMENTAL POSITION-INDICATING SYSTEM

• US 3,732,557 A
• Filed: 05/03/1971
• Issued: 05/08/1973
• Est. Priority Date: 05/03/1971
• Status: Expired due to Term

• Current Assignee: David C. Evans, Sutherland, Ivan E.
• Original Assignee: David C. Evans, Sutherland, Ivan E.
• Inventors: Sutherland, Ivan E., Evans, David C.
• Primary Examiner(s): Trafton, David L.
• Application Number:
  US05/139,434
• Time in Patent Office: 736 Days
• Field of Search: 178/19,18 235/151.32 340/166R,324R,365L,365C
• US Class Current: 345/179
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer

Abstract

A system for digitally manifesting the position of a probe with reference to aligned sets of conductors. Orthogonally arranged sets of index conductors in a tablet, and circular structures with parallel sets of conductors are shown for shaft-position encoder applications. Individual conductors in space-related, aligned, repeating sets are separately energized by phasedisplaced signals which are proximity sensed to provide a phasemodulated signal that is digitally detected to manifest relative displacement. Incremental information may be supplemented by absolute position information, and the representative phasemodulated signals may be transmitted over long-distance communication links.

Claims

1. A displacement-indicating system, comprising:

at least one set of index conductors disposed in spaced relationship along a path of displacements to be indicated;

means for defining at least first and second operating states for said system;

means for providing a plurality of phase-offset electrical signals;

means for coupling said phase-offset electrical signals to different sets of said index conductors during said first and second operating states;

probe means for sensing a phase signal from said set of conductors;

phase detection means for receiving said phase signal from said probe means to manifest said displacement of said probe in relation to said set of conductors;

register means for manifesting a positional relationship of said probe means to said index conductors; and

means for coupling said phase detection means to differently actuate said register means during said first and second operating states, to provide coarse and fine position indications in said register means respectively during said first and second operating states.

2. A displacement-indicating system according to claim 1 wherein said register means comprises a digital register having a plurality of sections and wherein said sections Are differently connected to said phase detection means during said first and second operating states.

3. A system according to claim 1 wherein said set of index conductors are provided in a circular pattern.

4. A system according to claim 1 wherein said set of index conductors are provided in a flat configuration and further including an insulating sheet covering said conductors.

5. A system according to claim 1 including two sets of conductors orthogonally arranged to indicate displacements along substantially perpendicular paths.

6. A system according to claim 5 wherein said means for providing a plurality of offset electrical signals comprises means for providing such signals of a first and a second frequency and wherein said means for coupling comprises means for coupling said signals of a first frequency to one set of conductors and said signals of a second frequency to another set of conductors and said system further including filter means for frequency distinguishing signals applied to said phase detection means.

7. A system according to claim 1 wherein said index conductors are embodied in a flat tablet comprising a base layer and a cover sheet with said index conductors in the form of printed-circuit layers disposed therebetween.

8. A system according to claim 1 wherein said means for defining comprises a plurality of switch means.

9. A system according to claim 1 further including a display device coupled to said register means for exhibiting displacement.