Strain relief device for an electrical connector for high frequency data signals

A strain relief device for an electrical connector designed to be interconnected to another connector of the same type to connect two cables containing at least one twisted pair, wherein said at least one twisted pair has conductors connected in a connection block having elements by means of insulation displacement contacts to contact blades, adapted to ensure contact in an interface block having elements with the corresponding contact blades of the other connector, said strain relief device comprising two guillotines sliding in side grooves of said connection block, wherein the side edges of said guillotines form a 90° angle between them and a 45° angle in relation to the direction of movement of said guillotines during a clamping operation, such that the side edges of the two guillotines form a diaphragm when they approach one another;

• wherein each guillotine includes racks on both of its edges that block the guillotine when it slides in said grooves;
• wherein each guillotine includes a shoulder located in a recess formed by said side edges and extending alone a side edge of the guillotine;
• wherein, when a connection is made, the geometry of the elements comprising said connection block is the same as the geometry of the elements comprising said interface block, said geometry being adapted so that the differential mode impedance between the conductors of each pair and the common mode impedance between said conductors and the shielding of said pair are respectively equal to the differential mode impedance between said contact blades and the common mode impedance between said contact blades and the shielding of the connector;
• wherein said insulation displacement contacts and said contact blades are included in a dressing-block made of plastic material of cylindrical shape with a circular cross-section, said dressing-block being inserted into cavities of said connection block and said interface block, said cavities having conductive walls and a cylindrical share with circular cross-section;
• wherein said cavities into which said dressing-block is inserted comprise a first cavity of a first diameter located in said interface block and a second cavity of a second diameter located in said connection block, both cavities having the same axis and being connected by a cavity having the shape of a truncated cones wherein the second diameter is greater than the first diameter;
• wherein said connection block includes a rectangular cavity divided into four insulating sub-cavities by two orthogonal conductive walls ensuring the transition from the shielding between the cable part where the shielding of the pairs are in contact with the part of the cable where the pairs are separated;
• wherein the shielding of each pair ends in said second cylindrical cavity such that said rectangular cavity has no influence on the electrical parameters of the pair;
• wherein said dressing-block includes a closing lever which enables, when the closing lever is open, said contact blades to be installed before being connected to the conductors of the associated pair and to place said conductors encased in their insulating jacket into said insulation displacement contacts, the closure of said closing lever causing penetration of the sharp edges into said insulating jackets of said insulation displacement contacts connected electrically to said contact blades and thus enabling the electrical connection between said conductors and said contact blades to be made;
• wherein said share edges of the insulation displacement contacts form an integral part of said contact blades and are located at the end of said contact blades and transversally to said contact blades;
• wherein one of said contact blades is no longer than the other of said contact blades so that, in order to preserve a distance between said contact blades defined by the differential mode impedance, said sharp parts located at the end of said blades are shifted to avoid mutual contact;
• wherein each of said contact blades includes a rectilinear part and a portion where contact takes place comprising a stiff side, a rounded bump, and an inclined plane, so that when connection is made between said connector and another connector of the same type, the electrical connection between the contact blades of both connectors is made by the contact between the rounded bumps of the blades;
• wherein each of said contact blades is placed in a groove of the front part of said dressing-block located in said interface block, said groove including a recess located at the location of said portion where contact occurs so that said blade occupies said recess during its deformation when the rounded bump of each of the contact blades passes behind the rounded bump of the other contact blade during the connection;
• and
• wherein each of said contact blades has a constant thickness (T), and has an initial width (W) in its rectilinear part and a narrower second width (Wc) in the portion where contact is made with the corresponding portion of the contact blade of the other connector such that the common mode impedance is equal to:
• Zc = 60 ϵ ⁢ ⁢ r ⁢ Ln ⁢ ⁢ ( 1.9 ⁢ B 0.8 ⁢ W + T )
• where B=2H+T with H being the distance between the middle point of the base of the blade and the wall of the cavity, and is the same in the rectilinear part and in the portion where the contact takes place when Wc=W−1.25 T.