Drum indicator

Claim 2

In an indicator of the character described the combination of electromagnetic means including a single pole piece and two concentrically wound coils surrounding at least a portion of said pole piece, an indicator member with a single elongate permanent magnet attached thereto, means supporting said indicator member for rotational movement about an axis extending transversely of the longitudinal axes of said pole piece and said magnet between two alternate limit positions determined by said pole piece in each of which the attraction of said pole piece to one end of said magnet tends to restrain said indicator member against movement toward the other limit position, said indicator member adapted to indicate different conditions in said two alternate limit positions, said two coils being adapted for selective energization so that one coil produces a magnetic field oriented to repel said indicator member away from one of said limit positions and impel it to the other of said limit positions and the other coil produces a magnetic field oriented to repel said indicator member away from said other limit position and impel it back to said one limit position.

Claim 3

In an indicator of the character described the combination of electromagnetic means including a single pole piece and a single coil surrounding at least a portion of said pole piece, an indicator member with a single permanent magnet attached thereto, means supporting said indicator member for rotational movement about an axis extending transversely of the longitudinal axes of said pole piece and said magnet between two alternate limit positions determined by said pole piece in each of which the attraction of said pole piece to one end of said single magnet tends to restrain said indicator member againSt movement toward the other limit position, said indicator member adapted to indicate different conditions in said two alternate limit positions, said coil being adapted for energization so that when energized with a current of one polarity the resulting magnetic field will repel said indicator member away from one of said limit positions and impel it to the other of said limit positions and when energized with a current of opposite polarity the resulting magnetic field will repel said indicator member away from said other limit position and impel it back to said one limit position.

Claim 4

In an indicator of the character described the combination of electromagnetic means including a single pole piece and a single coil surrounding at least a portion of said pole piece, an indicator member with a single permanent magnet attached thereto, means supporting said indicator member for rotational movement about an axis extending transversely of the longitudinal axes of said pole piece and said magnet between two alternate limit positions determined by said pole piece in each of which the attraction of said pole piece to one end of said single magnet tends to restrain said indicator member againSt movement toward the other limit position, said indicator member adapted to indicate different conditions in said two alternate limit positions, said coil being adapted for energization so that when energized with a current of one polarity the resulting magnetic field will repel said indicator member away from one of said limit positions and impel it to the other of said limit positions and when energized with a current of opposite polarity the resulting magnetic field will repel said indicator member away from said other limit position and impel it back to said one limit position.

Claim 5

An indicator as set forth in claim 2 including another permanent magnet disposed to magnetically polarize said pole piece so as to influence said indicator member to assume a predetermined one of said limit positions when said coil is deenergized.

Claim 6

An electromagnetic indicator comprising a single elongate pole piece made of magnetic material, an indicator member that includes a permanent magnet, means mounting said indicator member for rotation on a fixed axis that extends substantially perpendicular to the longitudinal axis of said pole piece, said fixed axis being disposed so that said indicator member can rotate between first and second limit positions each determined by engagement of a portion of said indicator member with an end section of said pole piece, said permanent magnet extending transversely of said fixed axis and having discrete north and south magnetic poles that are disposed on opposite sides of said fixed axis so that said north pole is closest to and said south pole furthest from said pole piece end section when said indicator member is in said first limit position and said south pole is closest to and said north pole furthest from said pole piece end section when said indicator member is in said second limit position, and electromagnet means for magnetizing said pole piece to impart either of two opposite magnetic polarities to said pole piece end section so as to cause rotation of said indicator member from one to the other of said two limit positions by magnetic repulsion of said magnet.

Claim 7

An electromagnetic indicator comprising a single elongate pole piece made of magnetic material, an indicator member that includes a permanent magnet, means mounting said indicator member for rotation on a fixed axis that extends substantially perpendicular to the longitudinal axis of said pole piece, said fixed axis being disposed so that said indicator member can rotate between first and second limit positions each determined by engagement of a portion of said indicator member with an end section of said pole piece, said permanent magnet extending transversely of said fixed axis and having discrete north and south magnetic poles that are disposed on opposite sides of said fixed axis so that said north pole is closest to and said south pole furthest from said pole piece end section when said indicator member is in said first limit position and said south pole is closest to and said north pole furthest from said pole piece end section when said indicator member is in said second limit position, and electromagnet means for magnetizing said pole piece to impart either of two opposite magnetic polarities to said pole piece end section so as to cause rotation of said indicator member from one to the other of said two limit positions by magnetic repulsion of said magnet.

Claim 8

An indicator as defined by claim 4 wherein said indicator member is provided with at least one predetermined legend, and further wherein said indicator includes means for concealing said legend when said member is in one of said positions and revealing said legend in the other of said positions.

Claim 9

An indicator as defined by claim 4 wherein said indicator member includes means for preventing direct contact between said magnet and said pole piece.

Claim 10

An indicator according to claim 4 wherein said last-mentioned means overlies said magnet in position to contact said pole piece in each of said two positions.

Claim 11

An indicator as defined by claim 4 further including nonconductive means on said magnet for maintaining a working gap between said pole piece and said magnet in both of said predetermined limit positions.

Claim 12

An indicator as defined by claim 4 wherein said electromagnet means comprises a single coil surrounding said pole piece.

Claim 13

An indicator as defined by claim 4 wherein said electromagnet means comprises two coils surrounding said pole piece.

Claim 14

An indicator as defined by claim 4 wherein said magnet is disposed in a plane extending through said shaft, and further wherein said magnet is notched so as to provide a gap between it and said shaft.

Claim 15

An indicator according to claim 4 wherein said magnet and said pole piece are located in a common plane that extends at substantially a right angle to said fixed axis and further wherein the said portion of said indicator member is a flat surface made of a nonmagnetic material that provides a nonmagnetic gap between said magnet and said pole piece.

Claim 16

In an indicator of the character described the combination of electromagnetic means including a single pole piece and a single coil surrounding at least a portion of said pole piece, an indicator member with a single permanent magnet attached thereto, Means supporting said indicator member for rotational movement about an axis extending transversely of the longitudinal axes of said pole piece and said magnet between two alternate limit positions determined by said pole piece in each of which the attraction of said pole piece to one end of said single magnet tends to restrain said indicator member against movement toward the other limit position, said indicator member adapted to indicate different conditions in said two alternate limit positions, a second fixed permanent magnet for magnetically polarizing said pole piece so that said pole piece will magnetically influence said indicator magnet to cause said indicator to assume one of said two limit positions, and said coil being adapted for energization so that when energized with a current of predetermined polarity the resulting magnetic field through said pole piece will influence said indicator magnet to rotate said indicator member to the other of said two limit positions.

Claim 17

In an indicator of the character described the combination of electromagnetic means including a single pole piece and a single coil surrounding at least a portion of said pole piece, an indicator member with a single permanent magnet attached thereto, Means supporting said indicator member for rotational movement about an axis extending transversely of the longitudinal axes of said pole piece and said magnet between two alternate limit positions determined by said pole piece in each of which the attraction of said pole piece to one end of said single magnet tends to restrain said indicator member against movement toward the other limit position, said indicator member adapted to indicate different conditions in said two alternate limit positions, a second fixed permanent magnet for magnetically polarizing said pole piece so that said pole piece will magnetically influence said indicator magnet to cause said indicator to assume one of said two limit positions, and said coil being adapted for energization so that when energized with a current of predetermined polarity the resulting magnetic field through said pole piece will influence said indicator magnet to rotate said indicator member to the other of said two limit positions.

Claim 18

An electromagnetic indicator comprising an indicator member mounted for rotation on a fixed axis, said indicator member having a pair of permanently magnetized poles with a magnetic axis that extends transversely of said fixed axis with said fixed axis located between said poles, and an electromagnet assembly comprising (1) a single pole piece extending at a right angle to said fixed axis with a section of said pole piece being disposed to intercept first and second portions of said indicator member so as to establish first and second limit positions respectively for said indicator member and prevent alignment of said magnetized poles with said pole piece, and (2) means including a coil for magnetizing said pole piece to impart either of two opposite magnetic polarities to said pole piece section whereby to magnetically influence said indicator to rotate from one to the other of said limit positions.

Claim 19

An electromagnetic indicator comprising an indicator member mounted for rotation on a fixed axis, said indicator member having a pair of permanently magnetized poles with a magnetic axis that extends transversely of said fixed axis with said fixed axis located between said poles, and an electromagnet assembly comprising (1) a single pole piece extending at a right angle to said fixed axis with a section of said pole piece being disposed to intercept first and second portions of said indicator member so as to establish first and second limit positions respectively for said indicator member and prevent alignment of said magnetized poles with said pole piece, and (2) means including a coil for magnetizing said pole piece to impart either of two opposite magnetic polarities to said pole piece section whereby to magnetically influence said indicator to rotate from one to the other of said limit positions.

Claim 20

An indicator according to claim 14 wherein said means for magnetizing said pole piece also comprises a permanent magnet with magnetic poles oriented so as to magnetically influence said indicator member to assume and remain in said first limit position when said coil is deenergized.