U.S. patent number 3,573,811 [Application Number 04/655,641] was granted by the patent office on 1971-04-06 for magnetically operated two position electrical indicator.
Invention is credited to William A. Knecht.
United States Patent |
3,573,811 |
Knecht |
April 6, 1971 |
MAGNETICALLY OPERATED TWO POSITION ELECTRICAL INDICATOR
Abstract
An indicator to show either of two conditions of an electrical
circuit and including an electromagnetic structure with poles and
coil means to energize the poles alternatively to either magnetic
polarity, and also including a permanently magnetized armature with
indicia thereon, either directly or on an attached member, the
electromagnetic structure and armature with indicia being included
within a housing that has at least one window through which the
indicia may be seen to indicate whether the armature is in one or
the other of two end positions determined by the current in the
coil in response to the external circuit. The poles of the
electromagnet may cooperate with the permanently magnetized
armature to hold the latter in either of the end positions while
allowing easy transfer to the other end position when current flow
is reversed.
Inventors: |
Knecht; William A. (New
Hartford, CT) |
Family
ID: |
27075438 |
Appl.
No.: |
04/655,641 |
Filed: |
July 24, 1967 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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570937 |
Sep 8, 1966 |
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Current U.S.
Class: |
340/815.63;
340/815.65 |
Current CPC
Class: |
G08B
5/24 (20130101) |
Current International
Class: |
G08B
5/22 (20060101); G08B 5/24 (20060101); G08b
005/14 (); G08b 005/22 () |
Field of
Search: |
;340/373,378,366 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pitts; Harold I.
Parent Case Text
This is a continuation-in-part of my copending application Ser. No.
570,937 filed Aug. 8, 1966 and now abandoned.
Claims
I claim:
1. A microminiature electrical indicator comprising first and
second coils; a ferromagnetically soft core for said coils; first
and second ferromagnetically soft pole pieces extending in
substantially the same direction from opposite ends of said core
and spaced apart from each other; a permanent magnet pivotally
mounted between said pole pieces; an indicator member attached to
said magnet to pivot therewith and comprising an indicating surface
section, said indicator member comprising first and second abutment
surfaces; first and second switches each comprising an actuator arm
in the path of one of said abutment surfaces, respectively, and a
relatively stationary contact located adjacent to one of said
actuator arms to be engaged thereby; actuating circuit means
connecting said first and second switches to said first and second
coils, respectively, whereby said switches alternately close an
actuating circuit for said first coil and open an actuating circuit
for said second coil when said second switch is closed and close
said actuating circuit for said second coil and open said actuating
circuit for said first coil when said first switch is closed,
whereby energizing the closed one of said actuating circuits will
energize the one of said coils and thereby energize said pole
pieces to draw said magnet to its opposite locating to close the
other of said switches and thereby to close the other of said
actuating circuits while opening the energized actuator circuit to
halt current flow therethrough; and a housing comprising means to
view said indicating surface section.
2. The indicator of claim 1 in which said indicator member
comprises a substantially flat surface section and a downturned end
portion and said abutment surfaces comprise opposite edges of said
downturned portion.
3. The indicator of claim 2 in which said flat portion of said
indicator member substantially covers one surface of said magnet
and comprises, in addition, a pair of downturned stop members, one
of said stop members on each side of said magnet near one end of
said magnet.
4. The indicator of claim 2 in which both ends of said magnet are
defined by surfaces tapering to points at each end of said magnet,
said surfaces being substantially parallel to said pole pieces in
each extreme position of said magnet.
5. The indicator of claim 2 in which said housing comprises two
view windows, one of said windows being at one end of said housing
and the other of said windows being at one side of said housing
perpendicular to the axis on which said magnet pivots, and said
indicating surface section comprises first and second painted
portions on said downturned portion adjacent to said first window
whereby substantially only one color will be visible through said
first window when said magnet is in one of its end position and
substantially only the other color is visible through said end
window when said magnet is in the other of its end positions, said
indicating surface section also comprising first and second colored
portions of said flat portion adjacent to said second window
whereby only said first color will be visible through said second
window when said magnet is in one of its end positions and only
said second color will be visible through said second window when
said magnet is in the other of its end positions.
6. A magnetically operated indicator comprising: coil means
comprising first and second coils; a pair of spaced
ferromagnetically soft poles magnetically linked to said coil means
to be magnetically energized thereby when a current flows in said
coil means; a permanently magnetized armature pivotally mounted to
align itself in a first end position with respect to said poles
when a net current flows in one direction in said coil means and to
align itself in a second end position with respect to said poles
when a net current flows in the opposite direction in said coil
means, the permanent magnetic field of said armature having
sufficient strength to maintain said armature in either of said end
positions when no net current flows in said coil means; an
actuating surface controlled by said armature; electrical contact
points near said armature to be actuated by said actuating surface
in both of said end positions of said armature; first and second
terminals connected, respectively, to said first and second coils
to receive energizing currents, said terminals being connected to
their respective coils by said actuating surface so that current
flowing in either of said coils will move said armature to cause
said actuating surface to interrupt the circuit to the energizing
coil and prevent further current from flowing therethrough while
simultaneously completing the circuit to the other of said coils;
and an indicating member connected to said armature to move
therewith to indicate at all times which of said end positions said
armature is in.
7. The indicator of claim 6 in which said poles are in the form of
strips substantially longer than they are wide and substantially
wider than they are thick, and said armature is pivotally mounted
substantially midway between said poles with the axis of said
armature substantially parallel to the width dimension of each of
said poles, and at least a limited area of one end of said armature
makes contact with said poles, alternately, in each of said end
positions.
8. The indicator of claim 7 in which said poles have outer ends
bent inwardly to make contact with one end of said armature in said
end positions of said armature.
9. The indicator of claim 8 in which the tips of said outer ends of
said poles point substantially directly toward each other.
10. The indicator of claim 8 in which the tips of said outer ends
of said poles are bent back away from a direction facing each
other.
11. The indicator of claim 8 comprising, in addition: a dimple
formed in each of said poles in the region thereof to make contact
with the other end of said armature.
12. The indicator of claim 7 in which said armature has
substantially wedge-shaped ends and opposing surfaces of said
wedge-shaped ends extend substantially parallel to adjacent
surfaces of said poles when said armature is in said end
positions.
13. The indicator of claim 7 in which said armature has a
projection on each side thereof and said projections comprise said
limited area that makes contact with said poles.
14. The indicator of claim 6 in which said armature comprises
rounded ends substantially concentric with the axis of said
armature and having a radius slightly less than the distance
between said poles in the region of said armature.
15. The indicator of claim 14 in which said poles are strips of
ferromagnetically soft steel substantially longer than they are
wide and substantially wider than they are thick and are bent to
form partially circular portions substantially concentric to the
axis of said armature.
16. The indicator of claim 6 comprising, in addition: an actuating
member attached to said armature to move therewith and engaging
said indicating member to move said indicating member between first
and second indicating positions.
17. The indicator of claim 16 in which said indicating member
comprises a pivotal support pivoting about an axis substantially
perpendicular to the axis of said armature.
18. The indicator of claim 17 in which said indicating member
comprises edges defining a substantially radial slot and said
actuating member engages said slot in a portion thereof radially
spaced from the axis of said indicating member.
19. The indicator of claim 6 in which said coil means comprises two
solenoid coils wound upon an axis substantially perpendicular to
the axis of said armature.
20. An electrical indicator comprising: first and second coils;
first and second ferromagnetically soft pole pieces spaced apart
from each other and magnetically linked with said coils; an
armature comprising a permanently magnetized member movably mounted
to be attracted by said pole pieces, an indicating surface section,
and first and second actuator surfaces; first and second switches
each comprising one arm in the path of one of said actuator
surfaces, respectively; electrical circuit means connected to said
first and second switches and to said first and second coils
whereby said first coil is energizable when said first switch is
closed and said second coil is energizable when said second switch
is closed, said first coil being magnetically linked to said pole
pieces so that when said first coil is energized it produces a
magnetic field in said pole pieces to move said armature to open
said first switch and to close said second switch, said second coil
being magnetically linked to said pole pieces so that when said
second coil is energized it produces a magnetic field in said pole
pieces to move said armature in the reverse direction to move said
actuator surfaces to open said second switch and to close said
first switch; and a housing comprising means to view said
indicating surface section.
21. The indicator of claim 20 in which said indicator surface
section comprises a disc attached to said armature to rotate
therewith.
22. The indicator of claim 21 in which said disc has an axial
extension along one portion of its periphery and the edges of said
axial extension form said actuator surfaces.
23. The indicator of claim 22 in which said one arm of each of said
switches is a movable arm positioned to be moved by said actuator
surfaces and each of said switches comprises, in addition, a
relatively stationary contact located adjacent to its said movable
arm to be engaged thereby to close the respective switch.
24. The indicator of claim 23 in which each of said movable arms
comprises a pair of elongated resilient numbers connected together
at one end and engageable by said abutment surfaces at the other
end.
25. The indicator of claim 22 in which said axial extension is a
portion of a circular cylinder.
26. The indicator of claim 22 in which said axial extension
comprises two flat portions making an obtuse angle with each other
and the radially outward surface of one of said portions is colored
differently than the radially outwardly facing surface of the other
of said portions and said housing comprises a window facing said
portions and through which only one of said portions at a time may
be viewed.
27. The indicator of claim 20 in which said actuator surfaces are
conductive portions of a surface of said indicator member and said
one arm of each of said switches bears against said surface of said
indicating member to engage, alternately, said actuator
surfaces.
28. The electrical indicator of claim 20 in which said electrical
circuit means comprises first and second unidirectionally
conductive elements connected together so that only one of said
unidirectionally conductive elements can conduct at a time, said
first and second switches being connected in series with said first
and second unidirectionally conductive elements and with said first
and second coils, respectively; and an additional circuit means
connected to both of said unidirectionally conductive devices to
render them alternately conductive in accordance with applied
electrical signals, whereby when said first switch is closed said
first unidirectionally conductive device can be made conductive to
energize said first coil to produce a magnetic field to move said
armature to open said first switch and close said second switch and
when said second switch is closed said second unidirectionally
conductive device can be made conductive to energize said second
coil to produce a magnetic field of reverse polarity to move said
armature in the reverse direction so as to close said second switch
and open said first switch.
29. A magnetically operated indicator comprising: solenoid coil
means comprising first and second coils and having two ends; a pair
of spaced poles magnetically linked to opposite ends of said coil
means to be magnetically energized thereby when a current flows in
said coil means, each of said poles comprising a strip of
ferromagnetically soft material extending substantially parallel to
each other and spaced apart over a portion of their length by a
first distance and having their ends remote from said coil means
offset with respect to said portion so that said ends of said poles
are spaced closer to each other than said portion; a permanently
magnetized armature pivotally mounted to align itself in a first
end position with respect to said poles when a current flows in one
direction in said first coil and to align itself in a second end
position with respect to said poles when a current flows in the
opposite direction in said second coil, the permanent magnetic
field of said armature having sufficient strength to maintain said
armature in either of said end positions when no net current flows
in said coil means; an indicating member connected to said armature
to move therewith to indicate at all times which of said end
positions said armature is in; and switch means engaged by said
armature in said end positions and electrically connected in series
circuit with said coils to open the circuit to said first coil when
said armature is in said first end position and to open the circuit
to said second coil when said armature is in said second end
position.
30. The indicator of claim 29 in which said magnet is elongated and
has symmetrical opposite ends formed with sides tapering toward a
chisel point and with a flat area of dimensions small compared to
the dimensions of said sides at the extremity of at least one end
of said magnet.
31. The indicator of claim 30 in which the spacing between said
outer ends of said poles is less than the overall length of said
armature and greater than the width of said armature whereby one
end of said armature makes contact with said ends of said poles,
alternately, in the region of said armature between one of said
sides and the flat surface at said end.
32. A magnetically operated indicator comprising: coil means
comprising first and second coils; a pair of spaced
ferromagnetically soft poles magnetically linked to said coil to be
magnetically energized thereby when a current flows in said coil
means; a permanently magnetized armature pivotally mounted to align
itself in a first end position with respect to said poles when a
current flows in one direction in said first coil and to align
itself in a second end position with respect to said poles when a
current flows in the opposite direction in said second coil, the
permanent magnetic field of said armature having sufficient
strength to maintain said armature in either of said end positions
when no net current flows in said coil means; an indicating member
connected to said armature to move therewith to indicate at all
times which of said end positions said armature is in; and first
and second switches comprising first and second resilient wires
extending substantially parallel to said poles and on opposite
sides of said armature and mounted adjacent said coil means with
the free ends of said wires adjacent the ends of said poles remote
from said coil means, a pair of fixed rigid conductors located
adjacent said free ends of said wire with said wires resiliently
biased thereagainst, the end portions of said wires bearing on said
fixed conductors being bent outwardly to rub against said
conductors, said indicating member having means rigidly attached to
it to rotate back and forth with it, the outermost ends of said
wires extending into the path of motion of said last named means to
be engaged thereby to displace said first and second wires,
alternately, from contact with said fixed conductors, said first
and second switches being electrically connected in series with
said first and second coils, respectively, whereby said first
switch opens the circuit to said first coil when said armature is
in its first end position and said second switch opens the circuit
to said second coil when said armature is in its second end
position.
33. A magnetically operated indicator comprising: an insulating
support member; conductive areas on said member; coil means
comprising first and second coils; a pair of spaced
ferromagnetically soft poles magnetically linked to said coil to be
magnetically energized thereby when a current flows in said coil
means, said poles being soldered to said conductive areas adjacent
said coil means to conduct heat from said coil means to said
member; a permanently magnetized armature pivotally magnetized to
align itself in a first end position with respect to said poles
when a net current flows in one direction in said coil means and to
align itself in a second end position with respect to said poles
when a net current flows in the opposite direction in said coil
means, the permanent magnetic field of said armature having
sufficient strength to maintain said armature in either of said end
positions when no net current flows in said coil means; an
indicating member connected to said armature to move therewith to
indicate at all times which of said end positions said armature is
in; a switch means connected as a double-pole, single-throw switch
in series with said first and second coils to permit only one of
said coils to be energized at a time to attract said armature, said
switch means being physically located to be actuated by said
armature to disconnect the energized one of said coils and to
connect the other of said coils as said armature moves in response
to the attraction of one coil.
34. The indicator of claim 6 in which said indicating member
comprises a flat surface portion substantially perpendicular to the
axis of said pivotally mounted armature, a downturned portion
substantially parallel to said axis, and areas of first and second
colors located both on said flat surface portion and on said
downturned portion, said indicator comprising, in addition: a
housing comprising an end having a first view window and a side
substantially perpendicular to said axis and comprising a second
view window, said areas of first and second colors on said
downturned portion being adjacent to said first window whereby
substantially only said first color will be visible through said
first window when said armature is in one of its end positions and
substantially only said second color is visible through said first
window when said armature is in the other of its end positions,
said areas of first and second colors on said flat surface portion
being adjacent to said second window, whereby only said first color
will be visible through said second window when said armature is in
said one of its end portions and only said second color will be
visible through said second window when said armature is in said
other of its end positions.
35. A magnetically operated indicator comprising: coil means
comprising first and second coils; a pair of spaced
ferromagnetically soft poles magnetically linked to said coil means
to be magnetically energized thereby when a current flows in said
coil means; a permanently magnetized armature pivotally mounted to
align itself in a first end position with respect to said poles
when a current flows in one direction in said first coil and to
align itself in a second end position with respect to said poles
when a current flows in the opposite direction in said second coil,
the permanent magnetic field of said armature having sufficient
strength to maintain said armature in either of said end positions
when no current flows in said coil means; an indicating member
rigidly connected to said armature to move therewith comprising a
flat surface portion substantially perpendicular to the axis to
said armature, a downturned portion substantially parallel to said
axis, and areas of first and second colors located both on said
flat surface portion and on said downturned portion; a housing
comprising an end having a first view window, and a side
substantially perpendicular to said axis and comprising a second
view window, said areas of first and second colors on said
downturned portion being adjacent to said first window whereby
substantially only said first color will be visible through said
first window when said armature is in said first end position and
substantially only said second color is visible through said first
window when said armature is in said second end positions, said
areas of first and second colors on said flat surface portion being
adjacent to said second window, whereby only said first color will
be visible through said second window when said armature is in said
first end position and only said second color will be visible
through said second window when said armature is in said second end
position; a switch means connected as a double-pole, single-throw
switch in series with said first and second coils to permit only
one of said coils to be energized at a time to attract said
armature, said switch means being physically located to be actuated
by said armature to disconnect the energized one of said coils and
to connect the other of said coils as said armature moves in
response to the attraction of said one coil.
Description
This invention relates to a magnetically operated indicator capable
of being made in microminiature size and having means to connect to
an electric circuit to produce a visual indication of selected
operating conditions in the circuit.
Because of the increasing complexity of electrical and electronic
equipment, the apparatus is frequently divided into modular units
each of which can be removed and replaced independently of the
others. This applies particularly to so-called integrated circuits
in which each module may be a relatively complex circuit printed on
a card or other substrate. This removal and replacement may be done
at a central location or, particularly in the case of equipment
intended for military operation, it may be done at the point of
operation. In either case, and particularly in the latter, it is
desirable, if not essential, that any fault in the operation be
easily detected and preferably be self-indicating.
As a result there has been established a requirement for a type of
indicating unit which must be extremely small, inexpensive, as
nearly foolproof as possible, and capable of giving unambiguous
indications of malfunction of the apparatus to which it is
connected with little or no continuous current drain. The indicator
of the present invention meets all of these criteria in a bistable
electromechanical device having at least one colored flag or
indicating member capable of being positioned in either of two
locations, one of which indicates faulty operation of the equipment
to which the device is connected and the other of which indicates
proper operation. The indicator member is mechanically connected to
a permanent magnet which is pivotally mounted adjacent to two
ferromagnetically soft pole pieces magnetically energized by a coil
structure that may include one or more coils. The two possible
positions of the indicator members correspond to a net current flow
in the coil structure in the two possible directions of such flow,
but because of the permanent magnetic field of the armature that
operates the indicator member, the indicator member can be held in
either position by the magnetomotive force of the armature in the
absence of any current in the coil structure. As a result the
current required to change the position of the indicator member
from one of its positions to the other need not be continued after
a change in position has taken place and therefore it is
unnecessary to provide a continued operating current in order to
maintain a continued indication of either faulty or proper
operation. This is important because it reduces the current drain
on the equipment, which could be a significant factor in the case
of equipment having a large number of indicators.
The indicator may be controlled by applying current pulses to the
coil structure whenever necessary to change the position of the
indicating member, or it may be controlled by connecting the
indicator to a voltage source capable of maintaining a continuous
current flow in the coil structure. In the latter case the
indicator preferably includes switching means to disconnect the
coil structure from the voltage source as soon as the indicating
member has moved to its alternative position, the switch means
being so arranged as to establish a new path of conduction through
the coil structure to produce a magnetomotive force capable of
causing the indicating member to return to the first position if
the operating condition of the equipment to which the indicator is
connected warrants such return.
The invention will be further described in connection with the
drawings in which:
FIG. 1 is a plan view, partly in cross section, of one embodiment
of an indicator constructed according to the invention;
FIG. 2 is a side cross-sectional view of the indicator of FIG.
1;
FIG. 3 is an end view of the indicator of FIG. 1;
FIG. 4 is a schematic diagram of an actuator circuit suitable for
use in the indicator of FIG. 1;
FIG. 5 shows a cross-sectional view of a modified indicator similar
to that of FIG. 1;
FIG. 6 shows a cross-sectional view of another embodiment of the
invention;
FIG. 7 is a plan view of the embodiment of FIG. 6 with part of the
structure broken away to show the interior construction;
FIGS. 8 and 9 are side and plan views of the modified switch
constructed in accordance with the invention;
FIGS. 10--15 show modified forms of stator pole and armature
arrangements in accordance with the invention; and
FIGS. 16 and 17 show another modification of the invention.
The indicator of FIG. 1 comprises a base 21 on which are mounted
two coils 22 and 23. A soft steel core 24, or other form of
ferromagnetically soft material, extends through the coils 22 and
23 and is tightly magnetically connected to two ferromagnetically
soft pole pieces 26 and 27 at its outer ends. These pole pieces are
bent around a barrier 28 and the outer ends of the pole pieces,
indicated by reference characters 26a and 27a, extend substantially
parallel to each other and in the same direction.
A shaft 29 mounted perpendicularly to the base 21 and pivotally
supports a magnet 31 having opposite ends 31N and 31S. The magnet
is of a type having high retentivity so that it remains permanently
magnetized with a north pole at the end 31N and a south pole at the
end 31S. The end 31N is formed by two surfaces 31a and 31b that
converge to a more or less sharp wedge shape while the end 31S is
similarly defined by two surfaces 31c and 31d that also converge at
a wedge shape, and in such a way that the edge 31b is substantially
parallel to the surface 31c and the surface 31a is substantially
parallel to the surface 31d. Moreover, for best magnetic circuit
operation, the surfaces 31a and 31d should be substantially
parallel to the ends 26a and 27a, respectively, of the pole pieces
26 and 27 when the magnet 31 is in the position shown in FIG. 1.
This position of the magnet 31 is one of its two end, or limiting,
positions. Arbitrarily, this position is defined as the malfunction
position, that is, the position in which the indicator warns that
the circuit to which it is connected is not functioning correctly.
The other end position, called the functioning position, would be
with the surfaces 31b and 31c substantially parallel to the ends
27a and 26a respectively.
Attached to the magnet 31 is a disc-shaped, nonmagnetic indicating
member 32 having a downwardly-turned edge 32a. The
downwardly-turned edge 32a extends over an arc of about 120.degree.
and the magnet 31 is so oriented with respect to this
downwardly-turned edge 32a that the end 31N points substantially
directly to the center of the edge 32a. To assist in maintaining
correct orientation of the indicating member 32 with respect to the
magnet 31, two tabs 32b and 32c are bent downwardly from the member
32 at points opposite the edge 32a. These tabs 32a and 32c not only
maintain the orientation of the magnet by lying adjacent to the
surfaces 31c and 31d, but they also act as stops to keep the
surfaces 31c and 31d from actually coming into contact with the
ends 26a and 27a of the pole pieces and sticking to the pole pieces
26 and 27 in either of the end positions of the magnet.
The indicator also includes switch means in the form of a pair of
switches, the first of which has a movable actuator arm 33 and a
relatively stationary post 34 attached to the base 21. The arm 33
may be affixed to the barrier 28, which is also preferably of
insulating material, and it may also be soldered, welded, or
otherwise connected to a pad 30. The other switch comprises a
movable arm 36, which may be anchored to a pad 35 and located by
the barrier 18, and a relatively stationary contact post 37 mounted
on the base 21. Both of the movable arms 33 and 36 are resiliently
biased toward their respective contact positions 34 and 37 so that
in the absence of obstruction, both of the switches would be
normally closed.
One form of obstruction to force the movable arms 33 and 36 away
from their fixed contact positions 34 and 37 consists of the sides
32d and 32e of the downwardly-turned edge 32a. In the position
shown in FIG. 1, the side 32d is pushed against the movable arm 33
to separate it from its contact post 34, thus opening this switch.
The location of the other side 32e is such that when the magnet 31
is in its other position, the side 32e presses against the movable
arm 36 and forces it away from the post 37 while at the same time
the side 32d moves away from the movable arm 33 and allows the
latter to return to its normal contact with the post 34.
At the other end of the indicator are four terminals 40--43, and
around the periphery of the base 21 are four walls 44--47 that form
part of the enclosure for the indicator. Three of these walls
44--46 may be opaque, while the fourth wall 47 has a transparent
window portion 47a. In actual fact, all of the walls 44--47 may be
made of transparent plastic most of which has been rendered opaque
by the layer of paint except for the area of the window 47a.
FIG. 2 shows a side view of the indicator of FIG. 1. The pole piece
27 extends from the end of the coil 23 where it is attached to the
end of core 24 out past the barrier 28 to the region of the magnet
31 although the end 27a of the pole piece has been broken away to
permit the magnet to be seen. The magnet is here shown pivotally
supported on a stud 29 affixed to the base 21 with a retaining
collar 48 to limit end play.
The movable arm 36 of the switch is, in this embodiment, divided
into two thin resilient members 36a and 36b, one of which may be
thicker or longer than the other so as to have a different resonant
frequency. The purpose of different resonant frequencies for the
two members 36a and 36b is to increase the chances that at least
one of them will at all times be in contact with the post 37 when
the surface 32e is not pressing against the members 36a and
36b.
Beneath the magnet 31 and the pole pieces 26 and 27 and between the
arms 33 and 36 is a small space within which may be located an
electronic circuit package 53 capable of controlling operation of
the indicator. The lower part of the barrier 28 may be a socket
into which the circuit package may be plugged. An extension 28a of
the barrier 28 may be provided to hold the circuit package in
place.
FIG. 3 shows an end view of the indicator and illustrates the
position of the window 47a in the wall 47 and with respect to the
downwardly-turned edge 32a of the indicating member. Part of the
wall 47 has been broken away to illustrate that the
downwardly-turned edge 32a has been divided into two sections 32a'
and 32a" which are painted different colors. When the magnet 31 is
in the position shown in FIG. 1, the section 32a" is in front of
the window 47a and the color of the section 32a" is therefore
visible through the window. It has been arbitrarily stated that
this position indicates malfunction of the electrical equipment to
which the indicator is attached. When the magnet 31 is in its other
end position, the color, or other indicia, of the section 32a'
fills the window 47a and affords a clear indication that the
equipment to which the indicator is connected is functioning
correctly. Instead of using the window in the end wall 47 of the
indicator, a window may be placed in an upper wall 49 through which
the flat surface of the indicating member 32 may be viewed. The
wall 49 is indicated in FIGS. 2 and 3 but has been removed in the
cross-sectional view in FIG. 1. However, the position of the
transparent window may be indicated in FIG. 1 by the position of a
circle 49a, and the surface of the indicating member 32 may have a
sector 32f painted a different color than the remainder of the
surface to be visible through the window 49a only when the
indicating member 32 is in the position shown.
FIG. 4 shows a typical schematic diagram of the electronic circuit
53 of FIG. 2. As may be seen, there are connections from this
circuit to the coils 22 and 23 and to the terminals 40--43. The
circuit comprises three transistors 56--58 of which the
emitter-collector circuits of the transistors 56 and 58 are
connected in series with the coils 22 and 23 and the switch arms 33
and 36. The two posts 34 and 37 are connected together to the
terminal 43 which in turn is connected to the positive terminal of
a source of operating voltage for the circuit. In the present
embodiment this voltage source is a 28-volt DC supply. Two diodes
59 and 60 are connected directly in parallel with the coils 22 and
23 to suppress inductive surges and to minimize radio frequency
noise that might be generated in the circuit. The junction between
the diode 59 and the coil 22 is connected to the collector of the
transistor 56, the emitter of which is connected to the ground
terminal 41. The emitter of the transistor 58 is also connected to
ground and its collector to the coil 23. A resistor 62 connects the
base of the transistor 56 to the terminal 42, which in turn is
connected to a positive bias voltage of about 4 volts, while the
bases of the transistors 57 and 58 are connected by means of two
resistors 63 and 64 to the terminal 40 which receives an input
voltage that governs the operation of the circuit and therefore the
operation of the indicator.
The circuit is so arranged that as long as the equipment to which
it is connected is functioning properly, a voltage not greater than
approximately +0.25 volt will be applied to the terminal 40
relative to the ground terminal 41, but as long as the equipment is
malfunctioning, a voltage of at least +3.6 volts will be applied to
the terminal 40. Let it be assumed that the indicator is in the
position shown in FIG. 1, which corresponds to an indication of
malfunctioning of the equipment to which it is connected. In that
condition, the arm 36 will be in contact with the post 37 but no
current will flow through the coil 22 because the transistor 56
will be nonconductive.
Now if it is assumed that the equipment being tested returns to a
proper functioning state, the voltage applied to the terminal 40
will be reduced to 0.25 volts or less and this will bias the
transistor 57 to the nonconductive state so that no current will be
drawn through the resistor 62. Thus the voltage at the base of the
transistor 56 will rise to a value of approximately +4 volts which
will render the transistor 56 conductive and make it possible for
current to flow from the terminal 43 through the post 37, the arm
36, the coil 22 and emitter-collector circuit of the transistor 56.
Current flowing in the coil 22 will cause the pole piece 26 to
assume a north magnetic polarity and the pole piece 27 to assume a
south magnetic polarity which, as shown in FIG. 1, will cause the
magnet 31 to flip to the reverse position breaking the connection
between the arm 36 and the post 37 and at the same time permitting
the arm 33 to contact the post 34. However, the coil 23 will draw
no current because the transistor 58 is biased to a nonconductive
state by the near-zero voltage applied to the terminal 40 during
the proper functioning of the equipment.
If the equipment under test again begins to malfunction, a voltage
of at least approximately +3.6 volts will be applied to the
terminal 40, which will bias both the transistors 57 and 58 to the
conductive state and permit current to flow through the transistor
58 and the coil 23, reversing the previous magnetic polarity of the
pole pieces 26 and 27 to drive the magnet 31 back to the position
shown in FIG. 1. This breaks the connection between the arm 33 and
the post 34 and deenergizes the coil 23 but by that time the
permanent magnet 31 is in position to hold the indicator 32 in the
position shown in FIG. 1. At the same time conduction of the
transistor 57 causes a current to flow through the resistor 62
which so reduces the voltage at the base of the transistor 56 that
the latter cannot become conductive even though its collector is
now connected via the coil 22, the arm 36, and the post 37 to the
supply voltage applied to the terminal 43.
Because the switches connected in series with the coils 22 and 23
are arranged so that each of these switches will be opened by
movement of either the arm 33 or the arm 36 very shortly after the
coil 23 or 22, respectively, has been energized, the flow of
current through the coils will be self-terminating, which is very
advantageous in keeping the power consumption of the indicator as
low as possible.
On the other hand, the switches can be eliminated entirely and the
coils 22 and 23 directly connected to the terminal 43 if the
resultant drain on the power supply can be tolerated. Minimum
energy consumption can still be obtained without having the
switches connected in series with the coils 22 and 23, if, in
addition, the transistor 57 and the resistors 62--64 are eliminated
and the transistors 56 and 58 are controlled directly by logic
pulses of the proper amplitude applied to their bases in such a way
that only one of the transistors 56 and 58 can become conductive at
a time.
Moreover, the electronic circuit package 53 need not be included in
the indicator itself but the terminals of the coils 22 and 23 can
be controlled by properly applied driving voltages from outside the
indicator. The coils 22 and 23 can even be combined into a single
coil with a bifilar winding or, by using a standard
double-pole-double-throw current-reversing switch, the two windings
of the coils may be combined into a single two-terminal winding.
Essentially what is required is that the poles 36 and 37 be
magnetically energized by a net flow of current in one direction or
the other in the energizing coil or coils, whether this current is
produced by connecting two terminals of a single coil to a voltage
source, first in one polarity and then in the other, or whether it
is produced by energizing one or the other of two coils, or whether
it is produced by energizing both coils simultaneously but one more
than the other to achieve a net current, and hence a net magnetic
field, in one direction.
FIG. 5 shows an indicator similar to that of FIG. 1 but with
modifications in the magnetic circuit components and in the
indicating member. However, many of the parts are identical with
those in FIG. 1 and are identified by the same reference numerals.
These include the coils 22 and 23, which, when energized by an
electric current, provide the required magnetic flux to operate the
indicator.
The pole pieces that channel this flux are somewhat differently
shaped than those in FIG. 1 and are designated by reference
numerals 126 and 127. The main difference between these and the
pole pieces 26 and 27 is that the outer ends 126a and 127a of the
pole pieces in FIG. 5 have an extra offset that brings them closer
together. The pole pieces 126 and 127 are bent inwardly around the
barrier 28 to form sections 126b and 127b, but instead of extending
straight from that point, are bent inwardly a second time around
the extension 28a to form the sections 126a and 127a that are
closer together than the sections 26a and 27a in FIG. 1. This is
permissible because, instead of the stops 32b and 32c to keep the
indicator member aligned with the magnet and to keep the surface of
the magnet from actually touching the pole pieces, the structure in
FIG. 5 has only a set of insulating tapes 66--69 on the faces
31a--31d of magnet. Even these tapes may be eliminated by making
the included angles between the surfaces 31a and 31b and between
the surfaces 31c and 31d slightly greater than the total angle
through which the magnet 31 pivots between its two extreme
positions so that the extreme tips of the magnet ends 31N and 31S
do not strike the pole pieces.
The magnet material must be chosen not only to retain its
magnetization but also to have relative low reluctance to form a
low reluctance path between the pole pieces. One satisfactory
material for the magnet 31 is 18 percent cobalt steel, which has
the desired magnetic properties and is also relatively easy to
shape.
The folded over edge of the indicating member 132 is not
cylindrical in the embodiment in FIG. 5 but is divided into two
relatively flat surfaces 132' and 132" at an obtuse angle to each
other. This presents a clearer image in the window 47a to make the
indication somewhat more definite than the rounded edge 32a in the
FIG. 1.
Finally, the outer ends 133a and 136a of the resilient arms 133 and
136 are bent slightly outwardly to present a better impact angle to
the abutment surfaces 132d and 132e. This angle, together with the
lack of rounding of the downwardly extending edge 132a, helps to
keep the abutment surfaces from jamming or wedging behind the arms
133 and 136.
FIG. 6 is a modified embodiment of the invention adapted for
mounting in a cylindrical container instead of a boxlike one. The
magnetic components are the same as in the embodiment of FIG. 5 and
therefore need not be described again. These components are mounted
in a cylindrical case 71 which may either be made of plastic or of
a nonmagnetic metal and which has an inner shelf 72 and a face
plate 73. The indicating mechanism includes an actuating member 74
attached to the armature 31 to pivot therewith. At the end of the
poles 126a and 127a is a support member on which is mounted a
bearing 77. A short shaft 78 is pivotally held within the bearing
77 and supports a disc 79. The disc 79 has a radial slot formed in
it by means of two-downwardly-turned edges 81 and 82 and the free
end of the actuating member 74 engages the edges of the slot so
that as the armature 31 pivots back and forth the actuating member
74 will pivot the disc 79 back and forth.
As may be seen in FIG. 7, the disc 79 has a segment 84 painted a
different color than the remainder of the disc to be visible
through a window 86 when the actuating member 74 is pivoted to the
opposite position from that in which it is shown in the drawing. In
this way, since the actuating member is radially spaced from the
center of the shaft 78, pivotal movement of the armature and the
actuator member 74 about the axis of the armature will cause a
corresponding pivotal movement of the disc 79 about an axis
perpendicular to the axis of the armature.
FIGS. 8 and 9 show a different form of switch arrangement for use
with the magnetic components of the invention as described in the
embodiment of FIG. 1--3, or FIG. 5. Whereas the embodiment
described hereinabove utilizes the indicating member merely as a
mechanical actuator for the switches, the embodiment in FIGS. 8 and
9 uses the indicating member, here identified by reference
characters 232, as one of the electrical components of the
switches. As shown in FIG. 8, the switch includes arms 87--89 to
press against the surface of the indicating member 232. The latter
is made of a nonconductive material, and, as shown in FIG. 9, has
two conductive areas 91 and 92 printed on the surface connected by
the switch arms 87--89. These arms are so placed that the arm 89
always bears against the conductive area 92 whereas the arms 87 and
88 alternately bear against the conductive areas 91 and 92. When,
as is indicated in FIG. 9, the arm rests against the conductive
area 92, there is a short circuit between that arm and the arm 89.
By connecting the arm 89 to the source of supply voltage and the
arm 88 to the coil 23, here indicated only diagrammatically, and by
connecting a battery 93 between the arm 89 and the centertap that
joins both the coils 22 and 23, the coil 23 will be energized, or,
more properly speaking, will be energizable, when a further switch
94 is closed. The closing of the switch 94 would, in accordance
with the purpose of the invention, be controlled by the electrical
apparatus that is being monitored, and when the switch 94 is closed
the magnetic field produced by the coil 23 will cause the
indicating member 232 to swing, or pivot, to its other end position
in which the conductive area 92 would short circuit the arm 87 to
the arm 89 and the arm 88 would no longer be resting on the area 92
but would, instead, be resting on the area 91. When the arm 87 is
short circuited to the arm 89, the coil 22 may be connected to the
battery 93 provided a further switch 96 is closed by the circuit
that controls the operation of the indicator. One of the problems
in the indicator of the present invention is to reach a proper
balance between the holding force that maintains the armature in
either of its two limiting positions and the force required to
shift the armature out of that position and into the other end
position. The magnetic circuit is most efficient when there is a
broad area of contact between the armature and the poles, but in
such a case the armature would tend to stick to the poles even when
the reverse current is applied to the coils.
FIGS. 10--15 show various pole and armature arrangements to
minimize the sticking and yet retain as much as possible of the
holding force. The poles 326 and 327 in FIG. 10 cooperating with
the armature 31 have their ends bent inwardly facing each other.
The poles are of sheet metal, much longer than they are wide and
much wider than they are thick, and the total area confronting the
armature at the ends of the poles 326 and 327 is an area equal to
the width times the thickness. As may be seen, only one end of the
armature 31 actually touches the poles but the other end comes
relatively close.
In the embodiment in FIG. 12 the ends of the poles 426 and 427 are
inwardly bent portions, but these inwardly bent portions are not at
the very ends of the poles. The armature 131 has outwardly
extending knobs at its ends to that only a relatively small area
makes contact with the poles, thus limiting the holding force.
In FIG. 11 the armature 231 is somewhat more blunt than the
armature 31 in FIG. 10 so that the surfaces 231a--231d do not come
flush against the poles 26 and 27. This means that the armature
pivots to an angle somewhat smaller than the angle between any of
the faces 231a--231d and a line drawn along the axis of the
armature from the end 231N through the pivot axle 29 to the other
end 231S.
In the embodiment on FIG. 13 the same type of armature 31 is used
as in some of the earlier embodiments, but each of the poles 526
and 527 has two bumps 526a and 526b and 527a and 527b positioned to
make contact with the ends of the armature 31.
In FIGS. 14 and 15 the armatures 331 have rounded ends concentric
with the pivot axis. In FIG. 14 this rounded-end armature pivots
between straight poles 26 and 27 to a position of minimum
reluctance. The magnetic efficiency is made even greater in the
embodiment of FIG. 15 where the poles 626 and 627 are bent to form
partially circular surfaces concentric with the pivot axis of the
armature 331.
The modification in FIGS. 16 and 17 includes many components
identical with the embodiment in FIGS. 1 and 2 and such components
have been given the same reference numerals and need not be further
described. The embodiment in FIGS. 16 and 17 differs from that in
FIGS. 1 and 2 in the arrangement of the permanent magnet, the
stator poles, the nonmagnetic indicating number, and the movable
resilient arms.
The magnet 431 in FIG. 16 is relatively slightly more blunt than
the magnet 31 in FIG. 1 but has the same general configuration with
tapering sides 431a and 431b at one end and 431c and 431d at the
other end. At the very tip of the magnet 431 the magnetic poles
431N and 431S are squared off. The ferromagnetically soft stator
poles 726 and 727 are displaced slightly inwardly at their tips
726a and 727a so that the tip 431N of the magnet strikes either the
pole portion 726a or 727a depending upon whether the magnet is in
one or the other of its end positions. It should be understood that
the magnet 431 could be reversed with the south magnetic pole at
the end identified by reference numeral 431N and the north magnetic
pole at the end identified by reference numeral 431S. The only part
of the magnet 431 that actually touches the pole portions 726a and
727a has a very limited area and does not interfere with reversal
of the position of the magnet by means of a field produced by
current in the appropriate coil 22 or 23.
The resilient wires that form the movable contacts to engage the
fixed contacts 34 and 37 are indicated by reference numerals 233
and 236, and, as may be seen, these arms are bent inwardly slightly
more than the arms 33 and 36 in the embodiment of FIG. 1. However,
the outer, or free, ends of the arms 233 and 236 are bent outwardly
so that they rub slightly in making contact with the fixed contacts
34 and 37, respectively, thereby keeping these contacts clean to
maintain the lowest possible impedance. In order to engage the
bent-out ends of the arms 233 and 236 properly, the
downwardly-turned flange 332a on the nonmagnetic member 332 maybe
required to have a slightly larger included angle as the flange 32
in FIG. 1.
As may be seen in FIG. 17, the end 727a of the 727 and the
corresponding end of the pole 726, is shaped so that it may be
soldered directly to a metallized portion on the surface of the
plate 21 for better heat conduction from the coils 22 and 23. This
soldering of the pole portion 727b can be done simultaneously with
or separately from the soldering of other components to the plate
21, which is preferably a ceramic plate with printed wiring
thereon.
While this invention has been described in terms of specific
embodiments, it will be recognized by those skilled in the art that
modifications may be made therein without departing from the true
scope of the invention as defined in the following claims.
* * * * *