Abstract:
A polarizing system is provided in a connector for electrically interconnecting the conductors of a flat flexible circuit to the conductors of a complementary connecting device. The flat flexible circuit has a longitudinal center-line and a pattern of polarizing holes therein asymmetrical to the center-line. A connector body member positions the flat flexible circuit thereon and has an asymmetrical pattern of polarizing posts insertable into the polarizing holes of the flat flexible circuit.

Description:
FIELD OF THE INVENTION 
     This invention generally relates to the art of electrical connectors and, particularly, to connectors for electrically interconnecting flat flexible circuitry. 
     BACKGROUND OF THE INVENTION 
     A flat flexible circuit conventionally includes an elongated flat flexible dielectric substrate having laterally spaced strips of conductors on one or both sides thereof. The conductors may be covered with a thin, flexible protective layer on one or both sides of the circuit. If protective layers are used, openings are formed therein to expose the underlying conductors at desired contact locations where the conductors are to engage the conductors of a complementary mating connecting device which may be a second flat flexible circuit, a printed circuit board or the discrete terminals of a mating connector. 
     A wide variety of connectors have been designed over the years for terminating or interconnecting flat flexible circuits with complementary mating connecting devices. However, problems continue to be encountered with such connectors. For instance, considerable problems can be created if a flat flexible circuit is positioned upside down in or on the connector. In other words, typically the circuit is positioned on the connector with the conductors of the circuit facing away from some form of carrier so that the conductors face the intended mating electrical interface. If the circuit is positioned on the carrier upside down, the conductors would face away from the intended mating electrical interface which would result in an unexpected open circuit condition at the interface. The present invention is directed to solving these problems in a polarizing system which would have very little impact on costs, lead times and tooling of the connector. 
     SUMMARY OF THE INVENTION 
     An object, therefore, of the invention is to provide a new and improved connector for electrically interconnecting the conductors of a flat flexible circuit to the conductors of a complementary connecting device, the connector including a polarizing system to prevent the circuit from being improperly oriented in the connector. 
     In the exemplary embodiment of the invention, the flat flexible circuit has a longitudinal center-line and a pattern of polarizing holes. The pattern is asymmetrical to the center-line of the circuit. The connector includes a body member for positioning the flat flexible circuit thereon. The body member has a pattern of polarizing posts insertable into the polarizing holes of the flat flexible circuit. 
     As disclosed herein, the connector body member comprises a generally elongated male body member having a leading edge at which the flexible circuit is positioned. The polarizing posts are located adjacent the edge. The polarizing holes in the flat flexible circuit are located adjacent a leading edge of the circuit. In the preferred embodiment, the circuit includes at least one polarizing hole on each opposite side of the center-line thereof, the holes being spaced different distances from the center-line. Therefore, the circuit cannot be mounted upside down on the connector body member. 
     Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with its objects and the advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: 
     FIG. 1 is a front perspective view of a connector embodying the concepts of the invention, in open condition; 
     FIG. 2 is a view similar to that of FIG. 1, with the flat flexible circuit being assembled to the connector; 
     FIG. 3 is a view similar to that of FIGS. 1 and 2, with the circuit fully assembled on the connector; and 
     FIG. 4 is a view similar to that of FIG. 3, with the cover in closed condition. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings in greater detail, and first to FIG. 1, the invention is embodied in an electrical connector, generally designated  10 , which includes a base in the form of an elongated male body member  12  having a leading edge  14  at which a flat flexible circuit is positioned, as described hereinafter. A pair of side guide walls  12   a  are formed at opposite sides of the male body member immediately behind leading edge  14 . A cover  16  is hinged to the body member for pivotal movement in the direction of arrow “A” from an open position shown in FIG. 1 to a closed position shown in FIG. 4. A pair of latch arms  18  are formed at opposite sides of the body member for engaging a pair of latch shoulders  20  at opposite sides of the cover to hold the cover in closed position securing the flat flexible circuit within the connector. A lip  21  runs the length of leading edge  14  of the body member spaced forwardly thereof. An elevated rib  22  runs the length of the body member behind leading edge  14  to provide a yieldable backing for the flexible circuit. 
     FIG. 2 shows a flat flexible circuit, generally designated  24 , in the process of being assembled to connector  10 . The circuit is elongated and includes a leading edge  26 . The circuit is typical in that it includes an elongated flat flexible dielectric substrate  28  having laterally spaced strips of conductors  30  on one side thereof facing away from male body member  12  for interconnection to the conductors of a complementary mating connecting device (not shown). For purposes of the invention, flat flexible circuit  24  has a center-line  32  which corresponds to a center-line  34  (FIG. 1) of elongated body member  12  of connector  10 . 
     The invention contemplates a polarizing system to prevent flat flexible circuit  24  from being assembled in connector  10  upside down wherein conductors  30  would not be exposed on top of the circuit as shown in FIG.  2 . In other words, as stated in the “Background”, above, if the circuit were assembled in the connector upside down, an unexpected open circuit condition would be created at the interface of connector  10  with the complementary connecting device. It can be seen in FIG. 2 that conductors  30  are intended to face outwardly from flat flexible circuit  24  for engaging the conductors of the complementary connecting device. If the circuit were assembled upside down, the conductors would face inwardly toward backing rib  22 , and there would be no conductive interface with the complementary mating connecting device. 
     The polarizing system of the invention includes a pattern of polarizing holes  36  formed through substrate  28  of flat flexible circuit  24  near edge  26  thereof. This pattern of holes is asymmetrical to center-line  32  of the circuit. In other words, the number and/or spacing of the holes on opposite sides of center-line  32  are different. Although multiple holes on opposite sides of the center-line are preferred to provide a balanced assembly of the circuit to the connector body member, the polarizing system of the invention contemplates a single hole on only one side of the center-line. The single hole would have a given spacing to one side of the center-line, and the circuit would be void of a hole at the same spacing on the opposite side of the center-line. 
     With the asymmetrical pattern of polarizing holes  36  in flat flexible circuit  24 , elongated male body member  12  includes a complementary asymmetrical pattern of polarizing posts or projections  38  near leading edge  14  (FIG. 1) of the body member. In other words, the number and spacing of polarizing posts  38  relative to center-line  34  in FIG. 1 is the same as the number and spacing of holes  36  relative to center-line  32  of the circuit in FIG.  2 . 
     FIG. 3 shows flat flexible circuit  24  fully assembled to male body member  12  of connector  10  between side guide walls  12   a , with the circuit extending rearwardly through a passage  40  in the body member. Leading edge  26  (FIG. 2) of the circuit is inserted into a slot  41  behind lip  21 . It can be seen that polarizing posts  38  of the body member are secured within polarizing holes  36  in the flat flexible circuit. It can be understood that the circuit now is secured to the body member. If the circuit was assembled upside down, polarizing holes  36  in the circuit would not match up positionally with polarizing posts  38  of the body member, and the circuit could not be secured in the connector. 
     FIG. 4 simply shows the connector with cover  16  pivoted and closed down onto body member  12  and held in closed position by latch arms  18 . Flat flexible circuit  24  now is held rigidly in the connector, with conductors  30  facing away therefrom for interconnection to the conductors of the complementary mating connecting device. 
     It should be understood that polarizing holes  36  in flat flexible circuit  24  and polarizing posts  38  on body member  12  of connector  10  provide a simply and effective polarizing system to ensure that the flat flexible circuit is not assembled upside down in the connector. However, this polarizing system also provides a means for keying any given circuit to any given connector. In other words, different patterns of conductors  30  are provided on different flexible substrates to provide different circuit geometries. A plurality of connectors could be coded for receiving specific circuits with specific geometries, and the asymmetrical patterns of holes  36  and posts  38  can be varied practically infinitely to match a given circuit with a given connector. This total customization of the connector assembly can be achieved very easily and with low cost. The holes in the circuit substrate can be made by optical tooling that has very little associated costs. The posts similarly can be changed with low cost tooling, as needed. These changes, along with the ability to change the conductor routing on the circuit, can result in a multiple of custom connectors with very little impact on cost, lead times and tooling. 
     It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.