Method and apparatus for precisely moving a motor armature

• US 4,870,306 A
• Filed: 10/08/1981
• Issued: 09/26/1989
• Est. Priority Date: 10/08/1981
• Status: Expired due to Term

• Current Assignee: Senshin Capital LLC (Intellectual Ventures LLC)
• Original Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Inventors: Petersen, Christian C.
• Primary Examiner(s): BUDD, MARK OSBORNE
• Application Number:
  US06/309,464
• Time in Patent Office: 2,910 Days
• Field of Search: 310/12-14, 310/30
• US Class Current: 310/12.31
• CPC Class Codes: H02K 41/03 Synchronous motors; Motors moving step by step; Reluctance motors H02K41/035 takes precedence

Abstract

Electromagnetic actuators are disclosed for precisely and directly incrementing an output member along a given generally linear path. Included in one actuator is a pair of assemblies, one of which is movable with respect to the other along the given path. A first of the assemblies includes means for producing a first magnetic field extending to the second actuator assembly in a manner generally transverse to the given path. The second actuator includes energizable means alongside the path and for producing a pair of opposed, approximately equal magnetic fields, spaced along the given path. Each of these opposed fields being aligned to cooperate with the transverse field to produce a force between the assemblies tending to centrally locate the assemblies with the transverse field between the pair of opposing fields.

Claims

1. In an electromagnetic actuator having a pair of actuator assemblies relatively movable with respect to each other for generating incremental movement to an output member to a plurality of positions along a given path in at least one of two opposite given directions, the improvement wherein:

one of said pair of assemblies includes means for establishing a magnetic field of one polarization for allowing said magnetic field to be directed generally transversely along a given distance to the other of said pair of assemblies;

said other assembly including a plurality of spaced first means selectively operable for establishing a plurality of electromagnetic fields each of which is selectively cooperable with said transverse field for creating a first electromagnetic force tending to drive one of the pair of relatively movable assemblies in said one given direction, and a plurality of second means arranged in alternating relationship with said first means and being operable for establishing a plurality of electromagnetic fields each of which is selectively cooperable with said transverse field for creating a second electromagnetic force tending to drive the one relatively movable assembly in the other of the two directions with a force generally equal to that created by the first means;

adjacent pairs of said first and second means being grouped in a space so that said given distance of said transverse field at least encompasses substantially equal sections of the adjacent pairs of said first and second means such that when the fields of energized adjacent pairs of said first and second means are intercepted by said transverse field they arrest movement of said one movable assembly and maintain it at one of the plurality positions, which position is generally between said intercepted adjacent energized pair of said first and second means, and further whereby movement in either of said two directions is achieved by selectively energizing only one of said adjacent pair of said first and second means intercepted by the transverse field.

2. In an electromagnetic actuator having at least a pair of actuator assemblies for generating incremental movement along a given path in at least one given direction, the improvement wherein:

one of said pair of assemblies includes means for producing a permanent magnetic field and for allowing said magnetic field to be directed generally transversely along a given distance to the other of said first and second assemblies;

said other one of said pair of assemblies includes a plurality of spaced electromagnetizable means, said electromagnetizable means when energized provide equal and opposite electromagnetic fields with respect to the adjacent ones of said electromagnetizable means, any adjacent pair of said electromagnetizable means is grouped within a space so that said given distance of said transverse field at least encompasses substantially equal sections of adjacent pairs of electromagnetizable means, whereby when one of said electromagnetizable means is energized it can interact with said transverse field to cause one cf the relatively movable pair of assemblies to move along the path in the given direction to drive an output member wherein said transverse field is moving relatively to said other one of said assemblies and is intercepted by an adjacent energized one of said electromagnetizable means in the given direction so as to interact therewith to arrest movement of the movable one of said assemblies at a desired one of the positions which is between said intercepted pair of energized adjacent pair of electromagnetizable means, and whereby continued incremental movement of the movable assembly is achieved by keeping the one of the intercepted energizable means energized which will drive the movable assembly in the given direction until the successive adjacent energized one of said electromagnetizable means in the given direction and intercepted by said transverse field arrests movement of the movable assembly between the adjacent energized pair of electromagnetizable means.

3. The actuator of claim 2 wherein said one assembly includes a core member and at least a pair of permanent magnets generally spaced apart by said given distance and being arranged so that opposing end portions of said magnets facing each other have the same magnetic polarization and are coupled to said core member so as to direct the magnetic field of said permanent magnets in the generally transverse direction.

4. The actuator of claim 2 wherein said electromagnetizable means are arranged in a pair of rows, wherein each row has the electromagnetiable means in generally side-by-side relationship and wherein each of said rows are arranged along said path on opposite sides of said one assembly.

5. The actuator of claim 2, 3, or 4 wherein said permanent magnets are of the rare earth type.

6. A method of selectively incrementing an output member to a plurality of positions along a given path in at least one of two opposite given directions by an electromagnetic actuator having a pair of actuator assemblies relatively movable with respect to each other wherein one of the pair of assemblies includes means for establishing a magnetic field of one polarization for allowing the magnetic field to be directed generally transversely along a given distance to the other of the pair of assemblies, and the other assembly including a plurality of spaced first means selectively operable for establishing a plurality of electromagnetic fields each of which is selectively cooperable with the transverse field for creating a first electromagnetic force tending to drive one of the pair of relatively movable assemblies in the one given direction, and a plurality of second means arranged in alternating relationship with the first means and being operable for establishing a plurality of electromagnetic fields each of which is selectively cooperable with the transverse field for creating a second electromagnetic force tending to drive the one relatively movable assembly in the other of the two directions with a force generally equal to that created by the first means wherein adjacent pairs of the first and second means are grouped in a space so that the given distance of the transverse field at least encompasses substantially equal sections of the adjacent pairs of the first and second means such that when the fields of energized adjacent pairs of the first and second means are intercepted by the transverse field they arrest movement of the one movable assembly and maintain it at one of the plurality positions, which position is generally between the intercepted adjacent energized pair of the first and second means comprising the steps of:

deenergizing only one of the intercepted pair of first and second means so as to move the one relatively movable assembly in the given direction; and

stopping the moving assembly at a next successive one of the plurality of positions, which position is between another adjacent pair of the first and second means intercepted by the transverse field in the one given direction by energizing the next successive one of the energizable first and second means in the given direction of movement of the moving assembly so as to create an equal opposing force on the movable assembly for stopping the same.

7. In an electromagnetic actuator having a pair of actuator assemblies, one of which is movable with respect to the other along a given path, the improvement wherein:

a first of said actuator assemblies includes means for producing a first magnetic field extending to the second of said actuator assemblies in a manner transverse to said given path; and

said second actuator assembly includes a plurality of coils successively located along said given path, each of said coils producing when energized, a pair of opposed approximately equal electromagnetic fields spaced apart from each other along said given path, each of said opposed electromagnetic fields being arranged to cooperate with said given transverse field in such a manner as to produce a force between said assemblies tending to centrally locate said assemblies with said given transverse field between one of said pairs of opposing electromagnetic fields, said coils being aligned in a plane generally normal to said transverse field.