GB2336948A

GB2336948A - BNC test connector

Info

Publication number: GB2336948A
Application number: GB9809337A
Authority: GB
Inventors: David Richard Fletcher
Original assignee: 3Com Technologies Ltd
Current assignee: 3Com Technologies Ltd
Priority date: 1998-04-30
Filing date: 1998-04-30
Publication date: 1999-11-03
Also published as: GB9809337D0

Abstract

A testing device for equipment 50 with an external coaxial connector comprising central connector 46 and cylindrical conductors 44 comprises central sprung probe 14 surrounded by sprung probes 16 such that the connections are made on insertion against a spring force, which force maintains good electrical contact.

Description

2336948 1 BNC Test ConneCo The present invention relates to an electrical

connection device particularly for use in a production test environment.

it is common, in the manufacture of electronic equipment, to include test procedures on the manufactured articles to ensure that they function correctly. Typically, a production item of electronic equipment, such as a device for use in a computer network, comprises one or more printed circuit boards carrying the components and circuitry necessary for the device to perform its desired function, an enclosure in which the circuit boards are positioned and a plurality of external connectors enabling connection to be made with the circuitry within the device enabling the device to function. Typically test procedures include making electrical contact with the external connectors to enable the application of electrical signals to the circuitry within the device and to record the response.

The present invention is concerned simply with the making of this electrical contact during the test procedure and the actual test procedures which are conducted do not form part of this invention.

One type of electrical connector which is well known to be used for signal inputs and outputs to electronic devices such as devices for use in a computer network, are BNC connectors. These connectors provide a two terminal coaxial connection and are therefore particularly useful for connecting cables carrying signals which are sensitive to external interference as the signal can be carried on a central conductor while a ground level can be maintained in the outer conductor which surrounds the inner conductor. A BNC connection is also in the form of a bayonet fitting, that is the male part of the of the connector, in addition to making the central contact, surrounds the outer shielding of the female part and has a mechanical C.\OFFICF-\WPWPDOCS\SPECS\BLUE\3COUBNC 2 interlock therewith. This therefore provides a very secure connection, both electrically and physically and is a widely used device.

In a test environment where it is desired to make and break electrical connections to the devices rapidly in order to enable as many devices as possible to be processed, the use of a "proper" BNC connector has disadvantages. In particular, it takes a significant amount of time to make and break thebayonet fixing and also standard BNC connectors may not be constructed to be sufficiently durable to be acceptable 'm a test environment before they fitil. Other similar coaxial type connectors may also present the same problems.

The present invention provides an electrical connection device for making electrical contact with a coaxial connector, the connector having a central conductor and an outer conductor, the electrical connection device comprising:

a body, a first contact finger arranged to move longitudinally between an extended position and a retracted position with respect to said body, at least one second contact finger arranged substantially parallel with said first contact finger and to move longitudinally between an extended position and a retracted position with respect to said body, and spring means arranged to bias said fingers, in the absence of external forces, to their respective extended positions, said first and second contact fingers being arranged such that electrical contact may be made between said first contact finger and said central conductor at the same time as electrical contact is made between said at least one second finger arranged and the outer conductor.

In the preferred construction, there is provided, for each contact finger, a housing mounted in said body and a spring, the spring being enclosed within the C:\OMCE\WPWIMWPDOCS\SPEC"LUE\3COM.BNC 3 is housing and the finger being arranged to move into and out of said housing.

In the preferred arrangement there are two contact fingers arranged to contact the outer or ground conductor of the coaxial device, these two being arranAed on either side of the first contact finger.

Preferably the first probe has a rounded end for facilitating location into and connection with the central conductor of a female BNC connector and the one or more second probes having a broad end to facilitate electrical connection with the outer ground connector.

In an alternative configuration the central probe may be configured so as to make proper electrical connection with the central conductor of a male BNC connector.

The invention also provides test equipment comprising one or more connection devices as defined above for making connection with equipment under test.

The use of spring probes as in the present invention means that good electrical connection with the BNC or other coaxial connector can be made simply by pushing the device into the connector, with the biasing maintaining good electrical contact. The arrangement of the present invention also permits some deviation from a proper central connection as it is possible still to make proper electrical contact even if the device of the invention is inserted into the connector to be tested at a slight angle.

The present invention will be better understood from the following description of a preferred embodiment given by way of example and with reference to the accompanying drawings Figure 1 illustrates a schematic diagram of the connector according to the preferred embodiment of this invention; C:\OMCE\WPWMWPDOCS\SPECS\BLUE\3COM.BNC 4 Figure 2a, b and c illustrate the connection of the device of Figure 1 with a female BNC connector; and Figure 3 is a schematic illustration of test equipment according to. this is invention.

Broadly speaking, a connector is shown for making test or temporary connection to a coaxial connector. One or more sprung probes are provided for each electrical connection which is to be made such that connection is made on insertion against a spring force, which force maintains good electrical contact.

Figure 1 illustrates the construction of a BNC test connection device according to the preferred embodiment of this invention. In particular test connector comprises a main body 12 and provides connections for the two conductors carried in coaxial cable 20.

For making connection with a BNC connector as will be explained in more detail below, device 10 includes one sprung probe 14 and two sprung probes 16.

Sprung probe 14 is arranged to move longitudinally within outer casing 15 and is sprung so as to be biased to the illustrated extended position. Similarly, sprung probes 16 are arranged to move longitudinally within respective outer casings 17 and are also sprung to the illustrated extended positions. Sprung probes of this type are commonly available and will not be described in detail in detail here. However it is sufficient to note that the probes 14, 16 are made of a conductive metal, for instance brass, as are the outer casings 15, 17 and the probes are arranged within the outer casings so that there is electrical connection therebetween.

Outer casings 15, 17 are fixedly mounted in main body 12 to enable connection of coaxial cable 20 to them. In particular, inner conductor 22 of coaxial cable 20 is connected, for instance by soldering, to outer casing 15 whereby. electrical connection is made to probe 14. The outer braiding of coaxial cable 20 is gathered C:\OMCF-\VJPWTMWPDOCSSPECS\BLLTE3C0b4BNC into two bundles 24 which are connected, again for instance by soldering, respectively to the two outer casings 17 thereby making electrical connection between the braiding of coaxial cable 20 and probes 16. Once the connections have been made the overall device, or at least the electrical connections, may be covered in a protective sleeve.

In the test environment, device 10 is carried by an automatic insertion apparatus of a well known type which can apply the device to and remove the device from apparatus to be tested. Tle other end of the coaxial cable 20 can be terminated in any desired fashion and it may be, as illustrated in Figure 1, that it is terminated with a standard BNC connector-3 0 to enable connection to the testing circuitry.

Figure 2 iHustrates the connection of device 10 as discussed above with reference to Figure 1 with a female BNC connector 40 provided on the exterior of apparatus 50. The circuitry widiin device 50 and the internal connection to connector are not shown in these figures and they are not significant for the understanding of this invention. However it is to be understood that device 50 can be any electronic device under test which contains circuitry requiring testing and having connections to BNC connector 40. Device 50 may for instance be a communications device for use in a computer network.

As can be seen in Figure 2, BNC connector 40 comprises an external cylindrical conductor 44 providing the ground connection and central conductor 46 which typically carries the signal connection. On the exterior of cylindrical conductor 44 are provided lugs 45 which, in a normal operation of the BNC connector, enable the bayonet fitting of the male connector onto female connector 40. Figure 2a illustrates these parts and shows connector 10 ready for connection with connector and with probes 14, 16 in their fidly extended positions.

Figure 2 b illustrates the connection of device 10 to connector 40 after insertion. As is apparent, central probe 14 is in contact with central conductor 46 Ci\OFFICE\WPWPDOCS\SPECS\BLUE\3COMBNC 6 while probes 16 are in contact with two portions of cylindrical conductor 44. Probes 14, 16 are sprung and it will be seen that they have all be deflected inwardly to some extent and the resilience of the spring loading of the probes ensures that preper electrical connection is maintained.

As the electrical connection is made by way of a simple straight line insertion it is very quick and simple to perform and further the only parts which are subject to significant wear are the spring probes and it is known that these can enable the order of 10,000 connections to be made before failure occurs.

Figure 2c illustrates how the connector according to this preferred embodiment can still make connection with female BNC connector 40 even in the event that it is not presented accurately but is presented at a slight angle. Because of the independent spring loading behind the three probes 14, 16 they can each deflect a different amount as required to enable proper connection and it is seen that, even in the configuration of Figure 2c, central probe 14 is still contacting central connector 46 while probes 16 contact two portions of cylindrical conductor 44.

It will be appreciated therefore that the invention provides a useful and advantageous test connector for a BNC device which is simple to use, that is to make and break the electrical contact, and enables the connection to many connectors before failure occurs.

Figure 3 is a schematic illustration of a item of test equipment incorporating connection devices as discussed above. In Figure 3 there is shown an item of electrical apparatus 50 within which is circuit board 51 carrying circuitry 52 which performs the required flinction of article 50. On the exterior of article 50 there are provided one or more BNC connectors 40 (in the illustrated case there are four connectors, but this is not limiting) which are connected to circuit board 51 and thereby to internal circuitry 52 to enable external connections to be made to apparatus C:\OFFICE\WPWTN\WPDOCS\SPECS\BLUE\3COM.BNC 7 in order that it can perform its intended function.

Test equipment 60 comprises a number of connection devices 10 arranged 'm a configuration complimentary to the arrangement of connectors 4Q on apparatus 50. Test equipment 60 also comprises test circuitry 62 connected to the connection devices 10 by way of cables 20.

In order to perform a test procedure, apparatus 50 and test equipment 60 are moved together so that connection is made between connection devices 10 and connectors 40 in a manner illustrated in Figure 2b or 2c. By way of these connections, electrical connection is made between test circuitry 62 and circuitry 52 within apparatus 50 enabling the application of test signals to circuitry 52 and the recording of the response.

It will be appreciated that in such a test environment the connecting devices according to this invention provide a simple but secure means to provide the electrical contact between test circuitry and circuitry under test thereby facilitating the overall testing procedure.

C:\OFFICE\WPWIMWPDOCSSPECSMLLTE\3COMBNC 8

Claims

CLAIMS:

1. An electrical connection device for making electrical contact with a coaxial connector, the connector having a central conductor and an outer conductor, the electrical connection device comprising:

2. An electrical connection device according to claim 1 further comprising, for each contact finger, a housing mounted in said body and a spring, the spring being enclosed within the housing and the finger being arranged to move into and out of said housing.

3. An electrical connection device according to claim 1 or 2 comprising two of said second contact fingers arranged one on each side of said first contact fmger.

C:\OMCE\WFIMWPDWSSPECS\BLUE\3CONtBNC 9

4. An electrical connection device according to claim 1 or 2 in which said first contact fmger has a rounded end to facilitate location into and electrical connection with the central conductor of a female BNC connector and the or each second contact finger has a broad end to facilitate electrical connection with the outer conductor.

5. An electrical connection device according to claim 1 or 2 'm which said first contact firtger is adapted to facilitate electrical connection with the central conductor of a male BNC connector and the or each second contact fmger has a broad end to facilitate electrical connection with the outer conductor.

6. Electrical testing equipment for making electrical contact with an electrical apparatus, the apparatus comprising at least one external connection in the form of a coaxial connector having a central conductor and an outer conductor, the testing equipment comprising a corresponding number of electrical connection devices, the or each such device being arranged to contract the or one of said coaxial connectors and comprising: body means; a first contact finger arranged to move longitudinally between an extended position and a retracted position with respect to said body, at least one second contact finger arranged substantially parallel with said first contact finger and to move longitudinally between an extended position and a retracted position with respect to said body, and spring means arranged to bias said fingers, in the absence of external forces, to their respective extended positions, said first and second contact fingers being arranged such that electrical C:\OFFICE\V;P%WWPDOCS\SPECSTLUE\3COUBNC contact may be made between said first contact fmger and said central conductor at the same type. as electrical contact is made between said at least one second finger arranged and the outer conductor.

C:\OMCF-\WPWrMWPDOCSSPECS\BLUE\3COnBNC