Abstract:
A double density plug and socket electrical connector employing the same form factor as existing 50 pin subminiature &#34;D&#34; connectors. Adapted for use on printed circuit boards the connector can compatibly interconnect 50 pin or 100 pin electrical connectors. The double fifty plug-socket connector can carry a multiple byte wide SCSI bus.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates generally to a plug and socket electrical connector, and more particularly, to connectors for printed circuits having a socket type spring contact strip and a plug type terminal strip insertable into the socket. 
     In view of the continuously progressive miniaturization of apparatus and components in electrical communications and transmission engineering, the construction of plug and socket connections becomes of constantly increasing importance, particularly with respect to increasing the number of electrical connections while maintaining or reducing the physical dimensions of the connector. A typical plug and socket connector for printed circuit boards is of the D-shaped type which provides the proper orientation of the plug into the socket. An example of an electrical connector is shown in U.S. Pat. No. 3,500,295 to Faber et al., wherein a plug and socket connector adapted for use on printed circuit boards is shown. The teachings of this patent are incorporated herein by reference. 
     As printed circuit boards become more complex embodying multiple layers within a board, the multiplicity of connections needed for communication with the printed circuit board increases while the area available on the board for placement of components and connectors is reduced. Typical D-shaped connectors are of a small size and are called subminiature D-shaped electrical connectors. These connectors carry up to a maximum of 50 electrical contacts. For electrical communication between computer equipment and peripherals a communications bus protocol is needed. One such protocol authorized by the American National Standards Institute (ANSI) is the Small Computer Systems Interface (SCSI). There is a growing interest within the industry for a connector that can provide more than a one byte wide SCSI bus while remaining within the same form factor or physical dimensions of an existing subminiature D-shaped 50 pin connector. It is desirable to maintain both upward and downward compatibility between connectors of existing and new designs. The needs expressed above lead to the creation of the connector of the present invention. 
     OBJECTS OF THE INVENTION 
     Accordingly, one object of this invention is to provide a 100 pin version of a plug and socket connector suitable for carrying more than a one byte wide SCSI bus while retaining the form factor of an existing subminiature D-shaped 50 pin connector. The 100 pin connector of the present invention possesses the physical outer dimensions of a subminiature D-shaped 50 pin connector while doubling the electrical contacts made within the same spacing as the 50 pin connector. The electrical contact width of a 50 pin connector is roughly halved by adding a space or spacer which is located between the reduced width contacts. To provide an electrical contact to the increased number of pins, a staggering of the pin connections to the contacts is made which allows for a crimped wire or other connection to the electrical contact posts. 
     The new connector provides compatibility between a 100 pin connector and a 50 pin connector thereby satisfying the ANSI requirements for downward and upward compatibility of electrical parts. Some of the 100 pin connections can be used to determine whether the 100 pin connectors is mating with another 100 pin connector, or mating with only a 50 pin connector. 
     The 100 pin connector of the present invention allows one part to be stocked in place of having two. The form factor, that is the physical space used upon a printed circuit board, remains the same as with a 50 pin connector. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a isometric view of a D-subminiature plug and socket electrical connector; 
     FIG. 2a is a sectional view of a connector socket; 
     FIG. 2b is a sectional view of a connector socket according to the present invention; 
     FIG. 3a is a top view of the plug portion of a connector; 
     FIG. 3b is a top view of the plug portion of the connector of the present invention; 
     FIG. 3c is a top view showing an alternative embodiment of the plug portion of the connector according to the present invention; 
     FIG. 4a is a bottom view of the plug portion of a connector. 
     FIG. 4b is a bottom view of the plug portion of the connector according to the present invention. 
     FIG. 5 is a sectional end view of a plug and socket connector according to the present invention; 
     FIG. 6a is a partial sectional view of a mated subminiature D-shaped 50 pin plug with the socket of the present invention; and 
     FIG. 6b shows the mated plug and socket of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Shown in FIG. 1 is a D-shaped subminiature plug-socket connector. Socket 10 is a unitaried body and can be made up of materials such as steel with zinc plating. Likewise, plug position 12 is of one piece construction and is designed to complementary engage with socket 10. The metallic housing is the support structure for the electrical connector. Electrical contacts 14 are spaced along the length of the electrical socket and can be made of a base material of beryllium copper and can have a plating of nickel-gold to decrease resistance across the contact junction. A thermoplastic type of material such as liquid crystal polymer or equivalent 18 provides for a dielectric separation between the housing 10 and the contacts 14. A electrical connection can be made to contacts 14 through wires 16 which are designed to mount directly to a PC board. Alternatively, socket 10 could connect to electrical wire connections rather than a PC board. The male plug portion of the electrical connector has posts 22 which are designed to connect to electrical wire cable such as a ribbon cable or a discreet wire bundle. The posts feed through to electrical contacts in the male plug which is not shown in this view. 
     The wire cable can be 50 pairs of 28 gauge wire forming a bundle of approximately 1/2 inch diameter. The cable must be highly flexible. Such cable is available from Madison Cable, 125 Goddard Memorial Dr., Worchester, MA 01603. 
     Holes 20 can be used to attach the plug to the socket or for attachment to a printed circuit board. A bail type latch not shown could also be employed on the connector. 
     The present invention places two electrical contacts within the same linear spacing as one contact of the existing subminiature D-shaped design. This is shown in FIGS. 2a and 2b. To maintain the lateral separation between the contacts 14 in the old design, a spacer 30 is placed therebetween. The spacers 32 between the narrow contacts pairs in the 100 pin connector of the present invention do not extend as far as the larger spacers 30 of the old design. Therefore, electrical connection can be made between a 50 pin old style plug mating with the 100 pin socket of the present invention. 
     Making effective electrical connection to the male plug portion of the electrical connector can be very difficult. Whether using a ribbon cable or a discrete wire bundle, it is often desirable to connect the cable to the contact post of the male plug without the use of solder. Due to the increased number of contacts necessary to be made for the present invention, staggered arrangement as shown in FIG. 3b is used. This arrangement is in contrast with the straight line post connections in of the subminiature D-shaped connector shown FIG. 3a. FIG. 3a, shows the posts 22 which are circular in shape. The posts may have widened areas for crimping onto electrical connective wire. Thermoplastic 18 separates each contact post. An alternative embodiment is shown in FIG. 3c where no thermoplastic material is used to separate the posts, separation being provided by the staggered relationship of adjacent posts. This provides easy access to the posts for crimping. 
     In the cross sectional view of FIG. 4a which is taken looking upward, the male plug portion of a subminiature D-shaped 50 pin connector is contrasted with that of the 100 pin connector of the present invention, which is shown in FIG. 4b. As seen in 4a, contacts 14 is separated by thermoplastic spacers 30 which extends outward nearly as far as the contacts. In FIG. 4b, each pair of contacts 14 are separated by large spacers 30 which protrude outward from the center of the plug nearly as far as the contacts while each individual contact in separated by spacer 32 of the same thermoplastic material 18. Spacers 32 do not extend from the center line of the plug as far as the large spacers 30. The two figures show how the 100 pin connector of the present invention can mate with a 50 subminiature D-shaped pin connector of the known art. 
     A cross sectional view of the unmated electrical connector is shown in FIG. 5. The socket portion 10 contains contacts 14 and electrical leads 16 having a dielectric encasement of thermoplastic material 18. The plug portion 12 has posts 22 and 23 leading in through the thermoplastic material 18 as shown. It can be seen that post 22 in FIG. 5 has a L-shaped, whereas post 23 does not. This is because of the staggered configuration of the electrical wire post contacts on the plug portion of the electrical connector. Every other post will be of the type having an L-shaped as depicted by numeral 22. It is desirable that the unique L-shaped posts be easily loaded into the plug or socket by conventional means to promote manufacturability of the connector. 
     A schematical representation showing the uniqueness of the present invention can be seen in FIGS. 6a and 6b, which are partial sectional views taken along lines 6--6 of FIG. 5 showing the connector in an engaged position and rotated 90°. FIG. 6a shows a subminiature D-shaped 50 pin connector mated to a 100 pin connector of the present invention. Contacts 14 mate together being laterally separated by large spacers 30. On the 100 pin socket side small spacers 32 separate each contact while spacers 30 separate each set of two contacts. FIG. 6b represents a 100 pin plug to 100 pin socket mating of an electrical connector. Electrical contacts 14 of the male plug mate directly opposite of the electrical contacts 14 of the female socket with large spacers 30 and small spacer 32 separating each contact 14 of the 100 pin connector. 
     Changes may be made within the scope and spirit of the intended claims which define what is believed to be new and deserving of patent protection.