Note: Descriptions are shown in the official language in which they were submitted.
105~882
This inYention relates to an electrical contact
pin, and particularly to an electrical contact pin for
mounting in a hole in, for example, a printed circuit board.
More particularly, this invention relates to
an electrical contact pin of the type described and claimed
in Canadian Patent Application No. 204,267 ~8395).
According to thisinvention there is provided
an electrical contact pin comprising first and second terminal
portions joined by an intermediate mounting portion comprising
two legs which are separated along a plane including the
longitudinal axis of the contact pin, the legs extending
parallel to the longitudinal axis of the contact pin but
being mutually offset and resiliently deformable towards
each other in directions parallel to the plane including the
longitudinal axis of the contact pin along which the legs
are separated, the legs sliding across each other in the plane
of separation during such deformation and the end of each leg
adjacent the first terminal portion being so shaped that on
insertion of the mounting portion into an interference fit
hole with the first terminal portion leading, the contact pin
has substantially no tendency to rotate about its longitudinal
axis.
Embodiments of contact pin according to the invention
will now be described by way of example with reference to the
drawings, in which:-
Figure 1 is a perspective view of a first embodiment
with part broken away,
Figure 2 is a side elevation of the contact pin
of Figure l;
Figure 3 is an end Yiew of the contact pin of
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Figure 1; 105~88Z
Figure 4 is a perspective view of a second embodiment
with part broken away;
Figure 5 is a side elevation of the contact pin o.
S Figure 4 prior to insertion into a hole;
Figure 6 is an end view on Figure 5;
~ igure 7 is a side elevation of the contact pin of
Figure 4 after insertion into a hole; and
Figure 8 is an end view on Figure 7. '.
The electrical contact pin 1 shown in Figures 1 to
3 comprises a first terminal portion 2 formed as a
substantially rectangular cross-section post, a second
terminal portion 3 formed as a substantially rectangular
cross-section post, and an intermediate mounting portion
4 comprising two legs 5 and 6 which are separated along
a plane 7 including the longitudinal axis of the contact
pin 1. The legs 5 and 6 extend parallel to the longitudinal
axis of the contact pin 1 but are mutually offset and
disposed on opposite sides of the plane 7. The legs 5 and
6 have smoothly rounded longitudinal outer edses 8 and 9.
The second terminal portion 3 is formed with a pair of
bosses 10 which provide a pair of shoulders 11 which
face the mounting portion 4 and extend transversely of
the longitudinal axis of the contact pin 1. The shoulders
11 serve to seat the contact pin 1 on the surface of,
for example, a printed circuit board (not shown) in known
manner.
As shown in Figure 3, the legs 5 and 6 initially
define a lateral dimenslon which is greater than the
d1amster of a hole, represented by a circle 12, ln, for
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lOS'~882
example, a printed circuit board, in which hole 12 the
contact pin 1 is to be mounted. Thus, as the ~ounting
portion 4 of the contact pin 1 is urged into the hole 12
the ]egs 5 and 6 are urged inwardly towards each other
and slide across each other at the plane 7 until they are
received in ~he hole 12, where they remain resiliently
biased against the wall of the hole 12 to secure the contact
pin 1 in the hole 12 prior to any subsequent soldering
operation. The rounding of the edges 8 and 9 of the legs
5 and 6 ensures that these edges do not unduly damage the
wall of the hole 12, which may be metal plated, and also
provides a relatively large surface area on the legs 5 and
6 for contact with the wall of the hole 12 to provide good
electrical and mechanical connection.
Such a contact pin is substantially as described in
the prior specification mentioned above, and is normally
acceptable for use in most circumstances except where
there must be substantially no rotation of the contact pin
about its longitudinal axis when the mounting pin is urged
into a hole, as the hole 12, as described.
In order that the contact pin should have substantially
no tendency to so rotate, in the embodiment shown in Figures
1 to 3 the end of each leg 5 or 6 adjacent the first
terminal portion 2 terminates in a point 13 lying in the
plane 7 and on a surface 14 of the first terminal portion 2.
The angle between the plane 7 and the opposite
surface 15 of each of the legs 5 and 6 at the point 13 is,
as indicated, approximately 15 at the outer surface 16 of
the legs 5 or 6, and approximately 23 at the surface 14 of
the first terminal portion 2.
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It has been found that with such a construction of
contact pin the forces acting to urge the legs 5 and 6
towards each other as the mounting portion ~ is urged into
a hole, as the hole 12, with the first terminal portion
leading, act in substantially directly opposed manner, and
thus there is substantially no tendency for the contact
pin 1 to rotate about its longitudinal axis.
Referring now to Figures 4 to 8, the contact pin 17
here shown comprises a first terminal portion 18 formed
as a circular cross-section post, a second terminal portion
19 formed as a circular cross-section post, and an
intermediate mounting portion 20 comprising two legs 21
and 22 which are separated along a plane 23 including the
longitudinal axis of the contact pin 17. The legs 21 and
22 extend parallel to the longitudinal axis of the contact
pin 17, but are mutually offset and disposed on opposite
sides of the plane 23. The second terminal portion 19 is
formed with a pair of bosses 24 which provide a pair of
shoulders 25 which face the mounting portion 20 and extend
transversely of the longitudinal axis of the contact pin
17. The shoulders 25 serve to seat the contact pin 17 on
the surface of, for example, a printed circuit board (not
sho~m) in known manner.
As shown in Figures 5 and 6, the legs 21 and 22
initially define a lateral dimension which is greater than
the diameter of a hole, represented by a circle 26 in
Figures 6 and 8, in, for example, a printed circuit board,
in which hole 26 the contact pin 17 is to be mounted. Thus,
as the mounting portion 20 is urged into the hole 26, the
legs 21 and 22 are urged inwardly towards each other and
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slide across each other at the plane 23 until they are
received in the hole 26 as shown in Figure 8, where they
remain resiliently biased against the wall of the hole 26
to secure the contact pin 17 in the hole 26 prior to any
subsequent soldering operation. The rounded surfaces
of the legs 21 and 22 ensure that the legs 21 and 22 do not
unduly damage the wall of the hole 26, which may be metal
plated, and also provide a relatively large surface area on
the legs 21 and 22 for contact with the wall of the hole
26 to provide good electrical and mechanical connection.
As Lndicated by the arrows in Figures 6 and 8, the
forces acting to urge the legs 21 and 22 towards each other
as the mounting portion 20 is urged into a hole, as the
hole 26, with the first terminal portion i8 leading, act
in substantially directly opposed manner and in the plane
23, and thus there is substantially no tendency for the
contact pin 17 to rotate about its longitudinal axis.
Although in the embodiment of Figures 4 to 8 the
contact is formed from circular cross-section stock, the
contact pin can otherwise be formed from stock having an
oval or an elliptical cross-section, the major and minor
axes of the contact pin cross-section being slightly
rotated with respect to the plane of separation of the
legs of the mounting portion of the contact pin so that
diagonally opposite quadrants of the mounting portion are
of different shape. Preferably the plane of separation
between the legs of the mounting portion is at a small
angle to the plane including the minor axes of the contact
pin cross-section.
When such a contact pin is inserted into a hole as
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described above for the contact pin of Figures 4 to 8,
only two sMall surface area portions of the quadrants of
the legs displaced furthest from the centre of the contact
pin, adjacent the plane of separation between the legs,
will contact the wall of the hole, and thus the forces
acting to urge the legs of the mounting portion towards
each other are substantially directly opposed and act in
the plane of separation of the legs. Thus, there is
substantially no tendency for the contact pin to rotate
as it is urged into a hole as described.
