U.S. patent number 3,617,958 [Application Number 04/861,299] was granted by the patent office on 1971-11-02 for contact spring.
Invention is credited to Rolland R. Roup, Ferdinand W. Schor.
United States Patent |
3,617,958 |
Schor , et al. |
November 2, 1971 |
CONTACT SPRING
Abstract
A filter connector assembly is disclosed which features an
electrically conductive contact spring composed of beryllium copper
or the like material and having a thin, elongated, and curved
central portion of uniform cross section together with latching
tabs or lugs at each end of the central portion. These latching
tabs are integral with the central portion of the spring and assume
a bent-up position so as to be substantially perpendicular to the
plane of the corresponding end part. The connector assembly
includes a tubular-shaped filter mounted in the assembly; a
connector contact pin which is inserted in and may be removed from
the central bore of the tubular filter and which may have an
external lead connected thereto in any desired manner; and the
aforementioned contact spring permanently retained or captivated
within the tubular filter after its initial insertion therein. The
filter itself takes the form of an inner ferrite tube and an outer
ceramic tube closely surrounding the ferrite tube, with
appropriately located conductive coatings applied to the surfaces
of both tubes. The filter may be of any desired type to give
whatever filtering effect is required in a particular application,
such as blocking interference signals, modifying pulse waveforms,
establishing or changing passbands for applied signals, etc. The
contact spring disclosed herein serves the dual functions of (a)
making a stable and constant electrical contact between the
conductive coating on the inner wall of the ferrite tube and the
contact pin and (b) mechanically holding or securing the contact
pin within the central bore of the ferrite tube. Another feature is
that the latching tabs or lugs are so shaped and dimensioned as to
fit within the ferrite tube bore with a clearance just sufficient
to permit initial insertion of the contact spring, the latching
tabs then serving to permanently retain the contact spring captive
within the filter.
Inventors: |
Schor; Ferdinand W. (Altadena,
CA), Roup; Rolland R. (Alhambra, CA) |
Family
ID: |
26811376 |
Appl.
No.: |
04/861,299 |
Filed: |
September 26, 1969 |
Current U.S.
Class: |
333/183;
439/843 |
Current CPC
Class: |
H01R
13/7197 (20130101) |
Current International
Class: |
H01R
13/719 (20060101); H03h 007/14 () |
Field of
Search: |
;333/76,79
;339/256,64,219 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Saalbach; Herman Karl
Assistant Examiner: Baraff; C.
Claims
What is claimed is:
1. A connector apparatus comprising: a tubular-shaped filter
mounted in said connector apparatus, said filter having a central
bore and having a conductive coating on the inner wall of said
bore; a connector contact pin means for insertion into and removal
from the central bore of said filter, said pin means having an
external lead connected thereto; and an electrically conducting
contact spring means for making electrical contact between the
conductive coating of said filter and said pin means and for
removably holding the latter within the central bore of said
filter, said spring means comprising an elongated central portion
and latching tabs or lugs integral therewith, said spring means
remaining captivated within the central bore of said filter by said
latching tabs or lugs.
2. A connector apparatus comprising: a tubular-shaped filter
mounted in said connector apparatus, said filter having a central
bore defining a conductive inner wall; a connector contact pin
means for insertion into and removal from said central bore; and an
electrically conducting contact spring means for making electrical
contact between said conductive inner wall and said pin means, said
contact spring means comprising an elongated curved central portion
and latching tabs integral with said central portion at the ends
thereof, said latching tabs being dimensioned to fit within said
central bore with clearance sufficient only to permit insertion of
the contact spring means therein, said latching tabs being formed
to permanently retain the contact spring means captive within said
filter after initial insertion and to further permit easy insertion
of said pins means into said central bore.
3. An electrical filter connector including a filter means for
blocking unwanted signals, said filter means comprising a hollow
cylinder, a connector contact pin adapted to be inserted in said
filter means and connected to an external lead, and an electrically
conducting contact spring means for providing constant electrical
contact between said pin and said filter means and for removably
holding said pin within said filter means, said contact spring
means comprising a long, narrow curved central section and latching
means for permanently captivating said contact spring means inside
said filter means, said latching means comprising a latching tab at
each end of said central section integral therewith and bent up to
a position to engage the respective outer ends of said hollow
cylinder.
Description
BACKGROUND OF THE INVENTION
With the increasing use of electronic equipment combined with
miniaturization of components and assemblies, the tendency is to
crowd considerably more equipment in a limited space than ever
before. This condition results in increased electrical interference
between equipments to the point where the performance of some of
the units is greatly degraded or even rendered useless.
Interference between equipments may sometimes be reduced by careful
shielding of components and connecting leads. Frequently, it is not
practical to shield all of the connecting leads. Also the
interfering field may be so great that shielding the leads does not
reduce the interference sufficiently. In such cases, it is
desirable to provide filters, usually of the low-pass type, at the
point where the leads enter the equipment.
One of the most efficient and least expensive ways of providing
such filtering is to assemble the filters into the connector
receptacle attached to the equipment. In this way, the interfering
currents are bypassed to the receptacle shell and return to ground
via the outer surface of the equipment chassis. Thus, they are
essentially prevented from entering the equipment and causing
undesirable interference.
Until recently, the connector filter assembly was constructed with
the filter assembled to each contact pin. In addition, the earlier
filter connectors were assembled with the filter contact pins
locked in place, thus requiring the leads to be soldered to the
contacts. With the introduction of multipin connectors carrying
hundreds of contacts, it proved more economical to assemble leads
to the contact pins using automatic crimping machines and providing
a connector construction which allows the contact pin to be pushed
into position and locked in place with an internal retention
spring. Present filter connectors provide this feature with lock-in
type filter pins in which the filters are permanently assembled to
the contact pin. While these give satisfactory performance, the
filter pins are quite expensive and their loss or breakage during
lead assembly greatly increases the cost of this operation.
By providing a connector construction in which the filter remains
captivated within the connector and only the contact pin is
removed, losses due to damaged contact pins during the operation of
lead attachment can be greatly minimized. The manner in which this
invention permits the use of such a filter connector construction
will be described subsequently.
SUMMARY OF THE INVENTION
This invention relates to a novel contact spring for use in
filter-type connectors.
An object of this invention is to provide a means for ensuring
constant electrical contact, under conditions of vibration and
temperature variations, between the inner contact surface of a
filter and a connector contact pin.
Another object is to provide a contact spring which can be inserted
into the filter and remain captivated to the filter despite
repeated insertions and removals of the contact pin.
A further object is to provide surface contact between the spring
and the connector contact pin on one side, and line contact between
the inner contact surface of the filter and the opposite side of
the contact pin, thus providing a low radio frequency impedance
between the contact pin and filter, a condition necessary for
obtaining the desired filtering action at high radio
frequencies.
A still further object is to permit the use of a captivated filter
in a filter connector, thus permitting the filter to remain within
the connector while the contact pin may be removed and reinserted
to permit the attachment of leads by crimping, soldering or other
means.
A salient feature of the invention is that the contact spring, when
once inserted into the filter, remains locked within the filter
unit while permitting the filter unit to be removed from the
connector or the contact pin to be repeatedly inserted and removed
without affecting the properties of the contact spring. Due to its
novel form, construction and spring qualities, the contact spring
can be removed from the filter only with difficulty after once
being inserted.
Another feature of the invention is that by permitting the filter
unit to remain captivated within the connector, only the contact
pin is handled during the process of attaching leads, making up
cables and assembling them to the connectors. This feature greatly
reduces the possibility of breakage of filters which are composed
mostly of brittle ceramic materials. It further greatly simplifies
and reduces the cost of automatic lead attachment, a process in
which the contact pins are carried on a tape and machine fed to a
lead attachment tool.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of the contact spring of the invention, in a
first embodiment thereof;
FIG. 1A is an end view of the contact spring of FIG. 1, showing the
outline of the latching tab at the right end of the contact spring
as seen when viewed from line 1A--1A in FIG. 1;
FIG. 2 is a side view similar to FIG. 1, but of a second embodiment
of the contact spring;
FIG. 2A is an end view similar to FIG. 1A, and showing the outline
of a modified form of latching tab, viewed from line 2A--2A in FIG.
2;
FIG. 3 is still another end view of the right-hand end of the
contact spring in a third embodiment having another modified form
of latching tab, this view corresponding to FIGS. 1A and 2A;
FIG. 4 is a longitudinal cross section of the filter and showing
the contact spring of FIG. 2 captivated within the central bore of
the filter, the connector contact pin being removed in this view;
and
FIG. 5 is a longitudinal cross section comparable to FIG. 4, but
showing the connector contact pin inserted in place within the
filter, the contact spring then assuming the deflected position
shown in this view.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to FIGS. 1 and 1A, there is shown the filter contact
spring 10 of the invention in its simplest form. The spring 10
consists of an elongated, curved central portion 11 of a uniform
rectangular cross section provided with a pair of latching tabs or
lugs 12, one at each end of the spring. Each of the tabs 12 is an
integral extension of the central portion 11, bent up into position
substantially perpendicular to the plane of the corresponding end
part of central portion 11. The spring's central portion 11 is made
to have a substantial curvature when in its rest or nondeflected
position as can be seen in FIG. 1. The central portion 11 follows a
uniform radius of curvature which is quite large in comparison to
any of the dimensions of the spring itself. The relative magnitude
required for the radius of curvature will be specified later, in
the description of FIG. 4. The contact spring 10 may be made of any
suitable electrically conductive material, such as beryllium
copper, for example. The contact spring may be formed from flat
wire stock, and heat treated either before or after forming. A
suitable finish such as silver or nickel plating followed by gold
plating may be provided in order to assure a high-quality
electrical contact.
FIGS. 2 and 2A illustrate an alternate and preferred embodiment of
the filter contact spring 10. It will be noted that in this version
the bent-up latching tabs or lugs 12a are made to be slightly wider
than the central body portion 11 of the spring. The relative
dimensions required for the end surfaces comprising tabs 12a will
be considered subsequently.
FIG. 3 illustrates still another embodiment of the contact spring
featuring a further modified shape for the latching tabs,
designated as 12c in this view. In this embodiment the tabs or lugs
12c have a substantially circular contour.
FIG. 4 shows a longitudinal cross section of the filter assembly
with the contact spring 10 in place. The filter consists of a
ferrite tube 21 disposed inside a ceramic tube 23. Both the inside
and the outside surfaces of the ceramic tube 23 are covered with
respective conductive coatings 25 and 26. These coatings which may,
for example, be silver coatings are insulated from each other and
therefore define a capacitor. It is customary but not always
necessary to split the inner silver coating 25 as by the space 28
so as to form two capacitors. The inner conductive coating 25 is in
intimate surface contact with a conductive coating 30 covering both
the inner and outer walls of the ferrite tube 21.
When the contact spring 10 is inserted into the filter and locked
into position as shown in FIG. 4, its radius of curvature is
increased so that the center of portion 11 presses on the inside
wall of the ferrite tube 21 at approximately the middle of the
tube. This pressure is transmitted through the central portion 11
to the end tabs 12a which bear against the outer ends of the filter
in the manner shown in FIG. 4. The tabs 12a, in this case, are
given outside dimensions just large enough so that they barely fit
into the center bore of the filter. This construction makes the
contact spring 10 almost impossible to remove once it has been
inserted in place and achieves a permanent retention of the spring
within the filter. With the tabs 12a thus latching or locking the
contact spring in place, no amount of vibration, temperature
variations, etc., can cause these tabs to become disengaged from
the end walls of the filter sufficiently to allow the spring to
fall out of the filter. Other important features are that the tabs
have a height such that they do not protrude beyond the outside
diameter of the filter; and further that the contact spring does
not block the opening at either end of the central bore in the
filter and thus permits easy entrance of the contact pin.
In the case of the modified end tabs as shown in FIG. 3, the
contour of the tabs and the chord subtended by the bend at each end
of the contact spring must be dimensioned to barely fit within the
central bore of the filter.
FIG. 5 shows the filter and spring assembly with the contact pin 32
inserted into the filter. When this is done, the contact pin 32
engages and deflects the contact spring 10 until it is practically
straight and is exerting substantial pressure against the contact
pin. The pressure is usually greatest at the middle of the segment
of the contact pin 32 which is enclosed by the filter but is
modified by irregularities of the inner wall 30 of the filter. The
opposite side of the contact pin is pressed against the conducting
inner wall 30 of the filter resulting in continuous electrical
contact between these two members. Thus the radio frequency
impedance between the contact pin 32 and the conducting inner wall
30 of the filter assembly 21, 23 is maintained at a very low value
approaching zero. The pin-to-filter electrical contact requirements
for the best possible filtering action are thus fulfilled.
The contact pin 32 can be removed whenever necessary, whereupon the
contact spring 10 returns to the position shown in FIG. 4. Note
that the assembly as shown in FIGS. 4 and 5 is symmetrical allowing
the contact pin 32 to enter with equal facility from either end.
This features permits the filter and spring assembly to be mounted
within the connector using either end for the contact pin
entry.
It is occasionally necessary in a multipin filter connector to
replace a filter which has become defective. If such a replacement
were not possible, it would be necessary to replace the entire
connector, an expensive procedure involving considerable labor plus
the added cost of a new multipin filter connector. With the filter
and spring assembly shown in FIG. 4 serving as a replaceable unit
in a multipin connector to permit filter replacement in accordance
with the present invention, it should be appreciated that the
captivation of the contact spring 10 within the filter is such as
to permit pushing or pulling the filter and spring assembly out
through narrow orifices without disengaging the contact spring.
Thus, application of the concept of this invention to multipin
filter connector assemblies permits a far more economical useage of
filters within the connector from the standpoint of both initial
cost and field serviceability.
Having now disclosed the concept for an improved contact spring for
filter pin connector assemblies and various preferred embodiments,
the following claims are appended to define what is considered to
be inventive:
* * * * *