U.S. patent number 3,676,819 [Application Number 04/884,167] was granted by the patent office on 1972-07-11 for contact-free potentiometer.
This patent grant is currently assigned to Siemens Aktiengesellschaft. Invention is credited to Werner Keller.
United States Patent |
3,676,819 |
Keller |
July 11, 1972 |
CONTACT-FREE POTENTIOMETER
Abstract
A stationary elongated armature body and a permanent magnet are
connected in a magnetic circuit. A guide plate of non-magnetic
material is interposed between the armature body and the magnet.
The guide plate is adjacent the armature body and has a recess
formed therethrough and a galvanomagnetic resistor is embedded in
the recess. The guide plate guides the magnet in gliding
relation.
Inventors: |
Keller; Werner (Olching,
DT) |
Assignee: |
Siemens Aktiengesellschaft
(Berlin and Munchen, DT)
|
Family
ID: |
5716478 |
Appl.
No.: |
04/884,167 |
Filed: |
December 11, 1969 |
Foreign Application Priority Data
|
|
|
|
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Dec 17, 1968 [DT] |
|
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P 18 15 160.5 |
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Current U.S.
Class: |
338/32R;
257/E43.004 |
Current CPC
Class: |
H01L
43/08 (20130101) |
Current International
Class: |
H01L
43/08 (20060101); H01c 007/16 () |
Field of
Search: |
;338/32,32H
;323/94H |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Kinberg; R.
Claims
I claim:
1. A contact-free, adjustable semiconductor potentiometer having a
plate-shaped, galvanomagnetic semiconductor resistor whose
resistance may be determined by shifting a magnetic field in
operative proximity therewith, the magnetic field being produced by
a magnetic circuit having a permanent magnet and a stationary
elongated armature body, said potentiometer comprising a guide
plate of non-magnetic material interposed between the magnet and
the armature body of the magnetic circuit, said guide plate being
adjacent to the armature body and having a recess formed therein
and said galvanomagnetic resistor being embedded in said recess,
said guide plate guiding the magnet in gliding relation.
2. A contact-free potentiometer as claimed in claim 1, wherein said
guide plate comprises a U-shaped frame affixed to said armature
body and forming a tunnel-like housing therewith enclosing the area
of said magnet.
3. A contact-free potentiometer as claimed in claim 1, wherein said
guide plate comprises a brass sheet and is cemented to said
armature body.
4. A contact-free potentiometer as claimed in claim 1, wherein said
magnet comprises a permanently magnetic cylindrical rod having a
pair of wafer-like poleshoes.
5. A contact-free potentiometer as claimed in claim 2, wherein said
guide plate further comprises a spring bolt mounted between said
magnet and abutting against said frame.
6. A contact-free potentiometer as claimed in claim 2, further
comprising a spiral spring in the area enclosed by said frame and
abutting an axial end of said magnet whereby the magnet is movable
relative to the spiral spring.
7. A contact-free potentiometer as claimed in claim 6, further
comprising a container of substantially hollow cylindrical
configuration having a closed bottom base and an open top base and
enclosing said potentiometer with said spiral spring adjacent said
bottom.
8. A contact-free potentiometer as claimed in claim 7, further
comprising a cover of substantially hollow cylindrical
configuration having an open bottom base and a closed top base and
adapted to engage said container in a threadlike manner as a
micrometer screw.
9. A contact-free potentiometer as claimed in claim 8, wherein said
guide means further comprises a spherical member mounted on the
opposite axial end of said magnet between said magnet and said
cover and abutting said magnet and said cover.
10. A contact-free potentiometer as claimed in claim 8, wherein
said container has a groove formed therein and said cover has at
least one bolt engaging said groove.
11. A contact-free potentiometer as claimed in claim 8, wherein
said cover has a border area on its cylindrical surface.
12. A contact-free potentiometer as claimed in claim 8, wherein
said cover has a recess formed in its top surface adapted to
receive an adjusting tool.
13. A contact-free potentiometer as claimed in claim 8, wherein
said cover has a ring shiftably mounted on its cylindrical surface
and having a scale division thereon.
Description
DESCRIPTION OF THE INVENTION
The invention relates to a potentiometer. More particularly, the
invention relates to a contact-free potentiometer.
The contact-free potentiometer of the invention comprises a
permanent magnet which may be removed across a stationary armature
body, and a galvanomagnetic resistor or field plate. Field plates
are bodies having electrical resistance which may be magnetically
controlled.
The principal object of the invention is to provide a new and
improved contact-free potentiometer.
An object of the invention is to provide a contact-free
potentiometer which includes a field plate adjustable to provide a
desired resistance magnitude which may be reproduced at any
time.
An object of the invention is to provide a contact-free
potentiometer having a resistance magnitude which, once adjusted,
may be maintained without variation for a long period of time.
An object of the invention is to provide a contact-free
potentiometer having a resistance magnitude which, once adjusted,
may be maintained without variation for more than fifteen
years.
An object of the invention is to provide a contact-free
potentiometer which is sealed dust tight and is shielded against
outside magnetic fields.
An object of the invention is to provide a contact-free
potentiometer which is almost completely insensitive to production
tolerances.
An object of the invention is to provide a contact-free
potentiometer in which a layer of non-magnetic material interposed
between the armature body and the magnet creates a space between
said armature body and said magnet, which remains constant in each
position of the magnet, thereby preventing the accumulation of
foreign bodies between said armature body and said magnet, so that
the potentiometer remains almost completely insensitive to
production tolerances.
An object of the invention is to provide a contact-free
potentiometer which functions with efficiency, effectiveness and
reliability.
In accordance with the invention, a contact-free adjustable
semiconductor potentiometer has a plate-shaped galvanomagnetic
semiconductor resistor whose resistance may be determined by
shifting a magnetic field in operative proximity therewith. The
magnetic field is produced by a magnetic circuit having a permanent
magnet and a stationary elongated armature. The potentiometer
comprises a guide plate of non-magnetic material interposed between
the magnet and the armature body. The guide plate has a recess
formed therein and the galvanomagnetic resistor is embedded in the
recess. The guide plate guides the magnet in gliding relation.
The guide plate comprises a U-shaped frame affixed to the armature
body and forming a tunnel-like housing therewith enclosing the area
of the magnet.
The guide plate comprises a brass sheet and is cemented to the
armature body. The magnet comprises a permanently magnetic
cylindrical rod having a pair of wafer-like poleshoes.
The guide plate further comprises a spring bolt mounted between the
magnet and abutting against the frame. The guide plate further
comprises a spiral spring in the area enclosed by the frame and
abutting an axial end of the magnet whereby the magnet is movable
relative to the spiral spring.
A container of substantially hollow cylindrical configuration has a
closed bottom base and an open top base and encloses the
potentiometer with the spiral spring adjacent the bottom. A cover
of substantially hollow cylindrical configuration has an open
bottom base and a closed top base and is adapted to engage the
container in a threadlike manner as a micrometer screw.
The guide plate further comprises a spherical member mounted on the
opposite axial end of the magnet between the magnet and the cover
and abutting the magnet and the cover. The container has a groove
formed therein and the cover has at least one bolt engaging the
groove.
The cover has a border area on its cylindrical surface. The cover
has a recess formed in its top surface adapted to receive an
adjusting tool. The cover has a ring shiftably mounted on its
cylindrical surface and having a scale division thereon.
In order that the invention may be readily carried into effect, it
will now be described with reference to the accompanying drawing
wherein:
FIG. 1 is a view, partly in section, of an embodiment of the
contact-free potentiometer of the invention;
FIG. 2 is a side view of the enclosed contact-free potentiometer of
the invention;
FIG. 3 is a top view of the embodiment of FIGS. 1 and 2, with the
cover removed;
FIGS. 4 and 4a illustrate the two extreme positions of the magnet
and armature body relative to each other; and
FIGS. 5 and 5a are two views of the layer of non-magnetic material
illustrating the position of the galvanomagnetic resistor.
In the FIGS., the same components are identified by the same
reference numerals.
As shown in FIGS. 1, 2 and 3, an armature body 4 is formed of a
non-ferrous, substantially planar, iron rod. The armature body 4 is
affixed to a U-shaped metal frame 8 and defines with said frame a
housing which encloses the area of a magnet 1, 2, 3.
The magnet 1, 2, 3 is a permanent magnet mounted for movement in
axial directions alongside the armature body 4 within the housing
formed by said armature body and the U-shaped frame 8. The magnet
comprises a permanently magnetic cylindrical rod 1 having a first
wafer-like poleshoe 2 at the upper end thereof and a second
wafer-like poleshoe 3 at the lower end thereof.
A spring bolt or buckle 9 is affixed to the poleshoes 2 and 3 of
the magnet 1, 2, 3 and abuts the inside surface of the U-shaped
frame 8. The spring bolt 9 thereby urges the magnet 1, 2, 3, in
addition to the magnetic force at the areas of the poleshoes 2 and
3 of said magnet, against a layer of non-magnetic material 5. The
layer of non-magnetic material 5 is interposed between the armature
body 4 and the magnet 1, 2, 3 and comprises a thin brass sheet
cemented to said armature body.
A recess 6 (FIGS. 5 and 5a) is formed through the layer 5 of
non-magnetic material. A galvanomagnetic resistor or field plate 7
(FIGS. 4 and 4a and 5 and 5a) is embedded in the recess 6 formed in
the layer 5 of non-magnetic material.
The magnet 1, 2, 3 and the metal frame 8 are housed in a steel
container 13 of substantially hollow cylindrical configuration
having a closed bottom base and an open top base. The magnet 1, 2,
3 is movable in the container 13 in axial directions thereof and in
gliding relation on the non-magnetic layer 5. The magnet 1, 2, 3 is
thus movable between a position in which it is at a minimum or
maximum distance from the galvanomagnetic resistor 7 positioned in
the recess 6 of the non-magnetic layer 5 and the maximum or minimum
distance from said galvanomagnetic resistor.
A spiral spring 14 is positioned around the lower end of the magnet
1, 2, 3 between the second poleshoe 3 of said magnet and the inside
surface of the container 13 and abuts said poleshoe and said
container. A steel cover 10 covers and seals the container 13. The
cover 10 is of substantially hollow cylindrical configuration
having an open bottom base and a closed top base and adapted to
engage the container 13 in a threadlike manner as a micrometer
screw.
The edge of the cover 10 which partly surrounds the container 13 is
joined by bolts with said container. The housing provided by the
container 13 and the cover 10 provides, without additional
measures, and in an advantageous manner, a dusttight sealing of the
potentiometer and complete protection against interfering magnetic
fields.
A spherical member 11 is mounted on the end of the magnet 1, 2, 3
adjacent the first poleshoe 2 and is positioned between said magnet
and the cover 10. In order to adjust the potentiometer to a
specific resistance value, the cover 10 is manually rotated, with
the assistance of a milled or border area 31 (FIG. 2) on its
cylindrical surface, or with the assitance of a screwdriver or
other suitable tool. The screwdriver is accommodated by a recess 30
formed in the outer top surface of the cover 10.
The rotating movement of the cover 10 is translated into an axial
movement of the magnet 1, 2, 3 via the spherical member 11. A
specific threading pitch between the container 13 and the cover 10
is selected to enable the adjustment and setting of the
potentiometer at a desired precision, without the requirement for
additional measures such as, for example, gears. The rotation of
the cover 10 is limited by bolts 12 provided in the engaging edge
of the cover 10 and functioning as stops for engaging a groove 25
formed in the container 13. The bolts 12 also prevent the housing
from being unintentionally disturbed by preventing the cover 10
from being unintentionally removed from the container 13. The
tightening of at least one bolt at the surface of the container may
prevent an adjusted resistance value from undesired variation.
In the final positions of movement determined in this manner, the
magnet 1, 2, 3 is positioned at a maximum and a minimum distance
from the galvanomagnetic resistor 7 positioned in the recess 6 of
the non-magnetic layer 5. The maximum position of the cover 10 is
illustrated by broken lines in FIG. 2.
The left-hand view of FIGS. and 4a illustrates the minimum position
in which the magnet 1, 2, 3 is a minimum distance from the
galvanomagnetic resistor 7. In the minimum position, the second
poleshoe 3 of the magnet 1, 2, 3 covers the field plate 7
completely, so that said field plate is subjected to a maximum
flux. The right-hand view of FIGS. 4 and 4a illustrates the maximum
position in which the magnet 1, 2, 3 is a maximum distance from the
galvanomagnetic resistor 7 positioned in the recess 6 of the
non-magnetic layer 5. In the maximum position, the second poleshoe
3 is a maximum distance from the field plate 7, so that the
magnetic flux to which said field plate is subjected is almost
zero.
The play or clearance in the threading between the container 13 and
the cover 10 of the housing of the potentiometer of the invention
is canceled out or compensated for in a preferred manner by the
spiral spring 14. The setting or reading of a specific resistance
value is provided with the assistance of two scale marks 15 and 16
provided on the outside of the potentiometer housing in the same
manner as for a micrometer screw. One scale mark 15 is positioned
on a ring 17 around the cylindrical surface of the cover 10 and may
be shifted thereon. The distance between the scale marks may be
selected in a manner whereby any desired exact adjustment may be
effected for desired resistance values. After adjustment, the ring
17 may be cemented to the cover 10.
Electrically conductive leads 18 extend from the potentiometer
housing, through the bottom of the container 13 thereof, to the
outside. A winding 19 is positioned around the permanent magnet rod
1 in order to adjust the magnetic field. The two ends of the
winding 19 are connected to electrically conductive leads which
extend from the potentiometer housing through the bottom of the
container 13 thereof via electrical contacts 21. One of the leads
20 from one of the ends of the winding 19 is shown in FIG. 3. The
bottom of the container 13, as shown in FIG. 3, is provided with
bolts or screws 22, 23 and 24 for fixing the various components of
the potentiometer of the invention in position in the potentiometer
housing.
While the invention has been described by means of a specific
example and in a specific embodiment, I do not wish to be limited
thereto, for obvious modifications will occur to those skilled in
the art without departing from the spirit and scope of the
invention.
* * * * *