U.S. patent number 3,825,878 [Application Number 05/395,475] was granted by the patent office on 1974-07-23 for flexible flat cable system.
This patent grant is currently assigned to Motorola, Inc.. Invention is credited to Carl Finger, John W. Pausche.
United States Patent |
3,825,878 |
Finger , et al. |
July 23, 1974 |
FLEXIBLE FLAT CABLE SYSTEM
Abstract
A housing having an elongated slot therein with opposed parallel
channels in the upper and lower surfaces adjacent the opening of
the slot and parallel spaced apart ridges extending transverse to
the longitudinal axis of the channels in the bottom surface of each
of the channels. An elongated cylindrical, silicone rubber member
having a diameter slightly larger than the width and depth of the
channels positioned in each of the channels so as to extend
slightly into the slot and a flexible flat cable having a fold
therein transverse to the parallel conductors and positioned in the
slot between the resilient members with each conductor parallel to
and overlying a ridge in the adjacent channel. Said cable further
defining openings between the conductors positioned in overlying
relationship to the resilient members and a portion of the cable
folded back over the housing and fixed in position by a strip of
plastic having openings therethrough to provide test point access
to the conductors.
Inventors: |
Finger; Carl (Glenview, IL),
Pausche; John W. (Norridge, IL) |
Assignee: |
Motorola, Inc. (Chicago,
IL)
|
Family
ID: |
23563191 |
Appl.
No.: |
05/395,475 |
Filed: |
September 10, 1973 |
Current U.S.
Class: |
439/493 |
Current CPC
Class: |
H01R
12/62 (20130101) |
Current International
Class: |
H05k 001/07 () |
Field of
Search: |
;339/17F,17L,17LM,59,61,75MP,174,176MF,176MP |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
700,490 |
|
Dec 1953 |
|
GB |
|
1,229,199 |
|
Apr 1971 |
|
GB |
|
Primary Examiner: Gay; Bobby R.
Assistant Examiner: Staab; Lawrence J.
Attorney, Agent or Firm: Parsons; Eugene A. Rauner;
Vincent
Claims
We claim:
1. A cable system comprising:
a. a flat flexible cable having a plurality of parallel spaced
apart conductors extending longitudinally therethrough and
maintained in position by a flexible, nonconducting material;
b. a connector housing having an elongated slot therein for
receiving an edge of a printed circuit board, said slot opening
outwardly along one side of said housing and extending inwardly to
form sides, spaced apart a distance slightly greater than the
thickness of the printed circuit board to be received therein;
c. said housing further defining first and second channels opening
into said slot and extending generally parallel with and spaced
from the opening of said slot, said first and second channels being
in opposite sides of said slot in generally parallel, opposed
relationship;
d. the bottom surface of each of said channels having a plurality
of parallel ridges formed therein extending transverse to the
longitudinal axis of said channels and spaced apart approximately
the same distance as the spacing between the conductors in the
flexible cable;
e. first and second elongated, resilient cylindrical members having
cross sectional dimensions slightly greater than the cross
sectional dimensions of said channels in said housing and
positioned in said channels so as to extend outwardly into said
slot;
f. said cable having a fold therein extending transverse to the
conductors with said fold being positioned in said slot so that the
conductors extend into said slot between said resilient members
with each conductor overlying and parallel to a ridge in said
channels; and
g. said cable further defining elongated openings in the
nonconducting material between the conductors and positioned
adjacent said resilient members for providing movement of
individual conductors.
2. A cable system as claimed in claim 1 wherein the resilient
cylindrical members are formed from material including silicone
rubber.
3. A cable system as claimed in claim 1 wherein the resilient
cylindrical members have a round cross section with the diameter
thereof being slightly larger than the depth and the width of the
channels.
4. A cable system as claimed in claim 1 wherein the housing
includes two generally mirror image halves with the junction
extending axially along the slot.
5. A cable system as claimed in claim 1 including a portion of the
cable extending outwardly from the slot folded back in overlying
relationship to a side of the housing and a generally flat
elongated strip affixed to the housing in overlying relationship to
said portion of cable and said side for holding said portion of
cable substantially immovable, said strip defining a plurality of
spaced apart openings therethrough each overlying a different
conductor in said portion of cable and the nonconducting material
being at least partially removed from the portion of conductor in
each of said openings so as to expose the portions of conductors.
Description
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
In electronic equipment utilizing a plurality of spaced apart
parallel printed circuit boards, it is convenient to provide
connection between the boards by means of a flat flexible cable
having spaced apart parallel conductors extending axially
therethrough. A great variety of connectors have been devised for
connecting the flat cables to the printed circuit boards. In
general, much difficulty has been encountered in providing a solid,
low resistance connection between each of the conductors in the
cable and each point on the printed circuit board.
2. DESCRIPTION OF THE PRIOR ART
In general, the prior art has attempted to include a springy
material, such as the flexible plastic U-shaped insert described by
McCullough in U.S. Pat. No. 3,319,216 entitled Connector for Flat
Cables or the metal spring fingers described by Schneck in U.S.
Pat. No. 3,102,767 entitled Electrical Connector for Flat Conductor
Cable, to apply pressure to the conductors in the cable and press
them against the contacts on the printed circuit board. However,
where a solid elongated springlike member is incorporated it
applies equal pressure along the entire cable and, since the
nonconducting material between the conductors is at least as thick
as the conductors, equal pressure along the entire surface of the
cable fails to provide a good contact. In the connectors utilizing
individual metal spring fingers the cost of the connector is
relatively high and the device is relatively complicated to
manufacture.
SUMMARY OF THE INVENTION
The present invention pertains to a cable system including a
housing having an elongated slot therein with a pair of opposed
parallel channels in the upper and lower surfaces thereof adjacent
the opening and parallel spaced apart ridges in the bottom surface
of each of the channels extending transversally to the channel. A
resilient cylindrical member having cross sectional dimensions
slightly larger than the channel and positioned in the channel so
as to extend slightly outwardly into the slot and a flat flexible
cable having a fold therein transverse to the conductors positioned
between the resilient members with their portions of the conductors
overlying the resilient members and parallel with and overlying a
ridge in the adjacent channel. The cable further defining openings
between the conductors to facilitate individual movement of the
conductors to afford compliance to said printed circuit board. A
portion of the cable being folded back over the housing with a
strip of material overlying the portion to maintain it immovable
and a plurality of spaced apart openings through said strip in
overlying relationship to bear portions of conductors to provide
test point access to said conductors.
It is an object of the present invention to provide an improved
flexible flat cable system.
It is a further object of the present invention to provide a
connector for a flexible flat cable wherein the contact between the
conductors of the cable and a printed circuit board inserted
therein is improved.
It is a further object of the present invention to provide a
flexible flat cable system which is simple and inexpensive to
manufacture.
These and other objects of this invention will become apparent to
those skilled in the art upon consideration of the accompanying
specification, claims and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to the drawings, wherein like characters indicate like
parts throughout the figures:
FIG. 1 is a view in perspective of an embodiment of the improved
cable system;
FIG. 2 is an enlarged sectional view as seen from the line 2--2 in
FIG. 1;
FIG. 3 is an enlarged sectional view as seen from the line 3--3 in
FIG. 1;
FIG. 4 is an exploded view in perspective of the cable system
illustrated in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the figures, the numeral 10 generally designates an
elongated housing having a generally rectangularly shaped cross
section. The housing 10 is formed of two elongated sections 11 and
12 each of which is approximately one-half of the housing 10 and
generally a mirror image of the other section. Each section 11 and
12 of the housing 10 is composed of a non-conducting material and
may be formed, for example, by molding plastic or the like.
An elongated slot 15 is formed in the housing 10, in the embodiment
illustrated at the junction of the sections 11 and 12, and extends
into the housing 10 so as to define spaced apart surfaces 16 and
17. The width of the slot 15 is slightly greater than the thickness
of a printed circuit board 20 (see FIG. 4) adapted to be inserted
in connecting relation therein. Further, the depth of the slot 15
is sufficient to receive the edge of the printed circuit board 20
in firm physical engagement therein. The opening of the slot 15 is
in a leading edge or surface 21 of the housing 10.
First and second channels 25 and 26 are formed in the surfaces 16
and 17, respectively, of the slot 15 so as to be generally parallel
with the opening or front surface 21 of the housing 10 and in
overlying or opposed relationship with each other. The channels 25
and 26 entend approximately the full length of the slot 15 and have
a generally rectangularly shaped cross section. The bottom surface
of each of the channels 25 and 26 has a plurality of spaced apart,
parallel ridges or corrugations formed therein. The ridges 30
extend generally transverse to the longitudinal dimensions of the
slot 15 and channels 25 and 26. Further, the ridges 30 are
positioned so that ridges in the channel 25 overlie ridges in the
channel 26.
A pair of elongated, cylindrically shaped, resilient members 35 and
36 are positioned in the channels 25 and 26, respectively. The
length of the members 35 and 36 is approximately equal to the
length of the channels 25 and 26 and the diameter of the members 35
and 36 is slightly greater than the width and the depth of the
channels 25 and 26. Because the cross sectional dimensions of the
members 35 and 36 is slightly larger than the cross sectional
dimensions of the channels 25 and 26, the members 35 and 36 are
frictionally engaged in the channels 25 and 26 and extend slightly
outwardly into the slot 15. It should be understood that the
members 35 and 36 are illustrated with a circular cross section but
they might have substantially any convenient configuration, such as
rectangular or trapezoidal. The members 35 and 36 should extend
outwardly into the slot 15 from the channels 25 and 26 sufficiently
so that the distance therebetween is smaller than the thickness of
the printed circuit board 20. In the present embodiment the members
35 and 36 are formed of silicone rubber material which is highly
resilient and has substantial memory so that it returns to
substantially its original shape when the circuit board 20 is
removed from the slot 15.
A flexible flat cable, generally designated 40, is formed of an
elongated ribbon 41 of nonconducting material having a plurality of
parallel spaced apart conductors 42 extending axially therethrough.
A fold is formed in the cable 40 transverse to the conductors 42
and the fold is positioned in the slot 15 so that opposite sides
thereof are adjacent and in overlying relationship to the surfaces
16 and 17 of the slot 15. The ridges 30 in the channels 25 and 26
are spaced apart a distance approximately equal to the spacing
between the conductors 42 in the cable 40 and are positioned so
that the portions of the conductors 42 in the cable 40 overlying
the members 35 and 36 are in parallel overlying relationship to the
ridges 30 in the adjacent channel 25 or 26 (see FIG. 3). A portion
of the non-conducting material 41 in the cable 40 which insulates
the portions of the conductors 42 overlying the resilient members
35 and 36 is removed to allow contact between the conductors 42 and
a plurality of spaced apart contact areas 45 on the surface of the
printed circuit board 20. When the printed circuit board 20 is
inserted in the slot 15 the resilient members 35 and 36 are
compressed slightly and the outwardly extending edges or surfaces
of the ridges 30 impart pressure on the portions of the conductors
42 overlying the resilient members 35 and 36 tending to force the
conductors 42 into tight physical and electrical contact with the
contact areas 45. The depressed portions between the ridges 30
provide a substantially reduced pressure on the cable 40 at areas
where electrical contact is not made so that insertion forced on
the printed circuit board 20 can be substantially reduced. To
further enhance the pressure applied to the cable 40 by the ridges
30, openings 46 are provided in the non-conducting material 41
between the conductors 42 in overlying relationship to the
resilient members 35 and 36. The openings 46 allow movement of
individual conductors 42 without transmitting the force applied
thereon to the adjacent nonconducting material 41. Thus, a simple
connector is formed which applies pressure to each of the
individual conductors 42 for a low resistance contact with a
printed circuit board 20 while requiring a relatively low insertion
force for the printed circuit board.
A portion of the cable 40 is folded over the upper surface of the
body 10 and a strip 50 of nonconducting material, which may be
similar to the material forming the body 10, is fixedly engaged in
overlying relationship thereto by some means, such as screws 51.
The screws 51 may also be utilized to hold the sections 11 and 12
in fixed engagement. The strip 50 has a plurality of spaced apart
openings 52 therethrough, which openings 52 are positioned so that
each overlies a different conductor 42 in the cable 40. Further, a
portion of the nonconducting material 41 is stripped from the
conductors 42 beneath the strip 50 so that bear conductors 42 are
available in the openings 52. Thus, the openings 52 provide a
readily available, test point access to the conductors 42 and,
hence, to the contact areas 45 and components on the circuit board
20.
While we have shown and described a specific embodiment of this
invention, further modifications and improvements will occur to
those skilled in the art. We desire it to be understood, therefore,
that this invention is not limited to the particular form shown and
we intend in the appended claims to cover all modifications which
do not depart from the spirit and scope of this invention.
* * * * *