Electric connector for flexible flat cables

An improved electric connector which permits insertion of a flexible flat cable in its insertion space without causing oblique insertion or misalignment between the exposed conductors of the cable and the terminals of the connector housing. The central feature of the electric connector resides in the lateral distance between the opposed side walls of the connector housing to be tapered with a dimension smaller than the width of the flexible flat cable.

FIELD OF THE INVENTION 
The present invention relates to an improvement in or relating to electric 
connectors for connecting centered flexible flat cables (FFCs) or centered 
flexible printed circuits (FPCs) to other printed circuits and electrical 
devices. 
DESCRIPTION OF RELATED ART 
As is well know, flexible flat cables (FFCs) and flexible printed circuits 
(FPCs) have been widely used in connecting different electric devices such 
as printed circuits to each other. The connector housing is composed of a 
ceiling wall, an opposed floor wall, and opposed side walls integrally 
connected to the opposed ceiling and floor walls to define a space for 
accommodating the FPC or FFC, and a plurality of terminals arranged at the 
same pitch as the conductors of the FPC or FFC are fixed to the connector 
housing. 
The lateral distance between the opposite parallel side walls is equal to 
or somewhat longer than the width of the flexible flat cable, thereby 
facilitating insertion of the flexible flat cable. 
The freedom of lateral movement of the flexible flat cable within the cable 
insertion space may allow the flexible flat cable to move laterally or 
obliquely. The length of the movement may be the same as the length 
defining the terminal pitch, thus causing misalignment of the conductors 
of the cable relative to the terminals of the connector housing. An 
incomplete connection between the conductors of the cable and the 
terminals of the electric connector may occur causing short circuits 
across selected terminals. 
SUMMARY OF THE INVENTION 
One object of the present invention is to provide an improved electric 
connector for flexible flat cables and printed flexible circuits where the 
connector is guaranteed to be free of such a misalignment between the 
conductors of the cable and the terminals of the connector housing which 
could cause incomplete connection therebetween when the cable is inserted 
in the connector housing. 
To attain this and other objects of the present invention an electric 
connector is provided for connecting a flexible flat cable having a given 
width to an electrical device. An insertion space in a dielectric housing 
is adapted to receive an end of the flexible flat cable through an 
insertion space opening. The insertion space is defined by a floor wall, 
an opposed ceiling wall and two opposed symmetrical side walls extending 
between the floor and ceiling walls. Electrical terminals are secured in 
the floor wall with each terminal having a contact portion extending from 
the floor wall into the insertion space for electrical connection to a 
respective exposed conductor on the flexible flat cable when the end of 
the flexible flat cable is positioned in the insertion space. 
The insertion space opening is defined by edges of the floor and ceiling 
walls and the opposed symmetrical side walls. The opposed side walls form 
a dimension therebetween, parallel to the floor wall, which increases as 
the side walls diverge from the floor wall to the ceiling wall. The 
longest dimension between the side walls being less than or equal to the 
width of the flat flexible cable so the that each longitudinal edge of the 
end of the cable contacts a respective side wall. This will cause the end 
of the flexible flat cable to form a curve about the longitudinal axis of 
the cable with the apex of the curve being located closer to the floor 
wall rather than to the ceiling wall. The ends of cable wall contact the 
opposed side walls causing the exposed conductors of the end of the cable 
to be in alignment with the contact portions of the terminals. An actuator 
is mounted to the housing to move from an open position, enabling the end 
of the cable to be inserted into the insertion space, to a closed 
position, forcing the end of the cable toward the first elongated wall 
creating an aligned engagement between the exposed conductors of the cable 
and the contact portions of the terminals.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in FIG. 1, an electric connector 5 for flexible flat cables 
comprises a housing 6 and a plurality of terminals 8 fixed to the housing 
6. The housing 6 comprises a ceiling wall 11, a floor wall 12 and opposed 
side walls 13 and 14 integrally connected to the ceiling wall 11 and the 
floor wall 12. A flexible flat cable insertion space 7 is defined by the 
ceiling wall 11, the floor wall 12, and the opposed side walls 13 and 14. 
The terminals 8 in the flexible flat cable insertion space 7 are arranged 
at the same pitch P as the conductors 2 of a flexible flat cable 1. 
A flexible flat cable (FFC) or flexible printed circuit (FPC) is stripped 
of its insulation so that the conductors 2 of the cable 1 are exposed at 
the end of the cable 1. The exposed conductors 2 of the cable 1 are made 
to contact the terminals 8 of the connector housing 6. 
The lateral distance between the opposed side walls 13 and 14 of the 
connector housing 6 increases from B to B' as the side walls 13 and 14 
extend from the floor wall 12 to the ceiling wall 11. The longest 
dimension B' at the ceiling wall 11 is equal to or shorter than the width 
A of the flexible flat cable 1. Each of the opposed side walls 13 and 14 
forms an equal and opposite angle with the ceiling wall. 
The stripped end of the flexible flat cable 1 is inserted into the flexible 
flat cable insertion space 7. As shown in FIG. 3B the longest lateral size 
B' of the cable insertion space 7 is shorter than the width A of the cable 
1. The end of the cable inserted into the cable insertion space will be 
yieldingly bent about its longitudinal axis in the form of circular arc. 
The apex of the arc is curved toward the floor wall 12. As a consequence 
the flexible flat cable 1 can be put in correct position relative to the 
terminals 8 of the connector housing 5 because no lateral movement of the 
cable 1 is permitted in the equilibrium condition attained by the 
resiliency of the cable 1 with its opposite longitudinal sides 3 and 4 
abutting on the opposite side walls 13 and 14 of the connector housing 6 
forming curved end portions C. Stated otherwise, there can be no 
misalignment of the cable conductor 2 relative to the connector terminals 
8, which misalignment would be caused by the lateral or angular movement 
of the cable conductors 2 if the lateral size of the cable insertion space 
7 were somewhat longer than the width of the cable 1. 
Next, as shown in FIG. 3a, fastening means 10 is used to push the curved 
cable against the floor wall 12 of the connector housing as indicated by 
arrow F, thereby bending the opposite longitudinal sides 3 and 4 of the 
flexible flat cable 1 forming bent end portions D to take a "U"-shaped 
form in cross section, and forcing the conductors 2 of the flexible flat 
cable 1 into close contact with the terminals 8 of the connector 5. 
The bending of the opposite longitudinal sides 3 and 4 of the flexible flat 
cable 1 along the opposite vertical side walls 13 and 14 of the connector 
housing permits automatic alignment of the cable 1 relative to the 
terminals 8 of the connector 5 with such accuracy that incomplete contact 
and short circuits are avoided. 
FIGS. 4, 5 and 6 show such an electric connector for flexible flat cables 
in detail. As shown, it has solder pieces 16 extending from housing 6 for 
fastening the connector to a printed circuit board (not shown). Also, 
cable fastening means 10 appears as actuator 17. 
The terminals 8 are arranged at same pitch as the pitch P at which the 
conductors 2 of the cable 1 are arranged. Each terminal 8 has a "U"-shaped 
cross section, and it has a solder tail portion 15 for soldering to a 
selected conductor on a printed circuit board. 
As shown in FIG. 3b, the longest lateral distance B' between the opposite 
side walls 13 and 14 of the connector housing is shorter than the width A 
of the flexible flat cable 1. This will cause the cable to form a curve. 
However, as shown in FIG. 2, the longest lateral distance B' may be equal 
to or slightly greater than the width A of the flexible flat cable 1. 
Either condition will work with this invention. 
To insert the flexible flat cable 1 into the cable insertion space 7, the 
actuator 17 is raised up in an unlocking position 18 (broken lines in FIG. 
6). The contact portions 9 of the terminals 8 extend up from the floor 
wall 12 of the connector housing. Since the flexible flat cable 1 will 
initially form a curve as shown in FIG. 3b or will be forced into a curve 
from a generally flat insertion as shown in FIG. 2, the exposed conductors 
2 face the floor wall of the connector housing. 
After insertion the flexible flat cable 1 in the connector housing, the 
actuator 17 is lowered to the locking condition 19 (solid lines in FIG. 
6), thus completing the insertion position of the cable in the housing. In 
this position the cable 1 is pushed against the floor wall 12 of the 
connector housing, changing its shape from the letter "C" to the letter 
"U" in cross section. In this position the conductors 2 of the cable 1 are 
forced into contact with the terminals 8 of the connector 1. Finally, the 
actuator 17 and cable are moved toward the housing thereby locking the 
cable and actuator 17 in the housing. 
As shown in FIG. 1 each side wall 13, 14 of the housing 6 has a tapered 
portion 20 extending at an angle from the ceiling wall 11 converging 
toward the floor wall 12 and a normal portion 21 extending at a right 
angle from the floor wall 12. The tapered and normal portions are joined 
together. 
As the fastening means 10 or actuator 17 is lowered into the locking 
position, applying a force F to the cable 1, the cable is curved in the 
form of a circular arc. This permits the opposed longitudinal sides of the 
cable 1 to yieldingly bend so as to be automatically guided toward the 
lateral alignment position relative to the terminals 8 by the tapered 
portions 20 of the opposite side walls 13 and 14. The resilience of the 
bent cable creates the equilibrium condition. Finally, the cable 1 is 
pushed against the floor wall 12 of the connector housing 6 by the 
fastening means 10 or actuator 17 so that the cross section of the cable 1 
is changed from "C"-shaped arc to a "U" shape, forcing the conductors 2 of 
the cable 1 into contact with the terminal contacts 9 of the connector 
housing 6, as seen from FIG. 3A. 
As may be understood from the above, the trapezoidal cable insertion space 
with the reduced lateral dimension has the effect of facilitating 
insertion of a flexible flat cable equidistant from the side walls and of 
aligning the conductors of the cable in the connector housing relative to 
the terminals of the connector housing. FIGS. 1, 2 and 3 show the 
connector housing as defining an enclosed space by its ceiling wall, floor 
wall and opposed side walls. It, however, should be noted that a connector 
housing having no ceiling wall 11 or floor wall 12 may be used. For 
example, the connector housing may have no ceiling, and it may be composed 
of a floor wall and opposite diverging side walls, thus permitting a 
flexible flat cable to be put in the open enclosure from the top, pushing 
the cable against the floor wall, which has terminals fixed therein.