Abstract:
An adapter for a sensor measuring a differential signal comprises two electrically conductive test-contact elements which are arranged in each case eccentrically relative to an axis of rotation in order to register respectively one partial signal of the differential signal. Moreover, two adjustment components, each rotatable about one of the two axes of rotation, are provided in the adapter for the adjustment of a variable spacing distance between the two test-contact elements. The two adjustment components are connected to one another in a force-fit manner.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application is a national phase application of PCT application No. PCT/EP2012/056987 (filed Apr. 17, 2012), and claims priority to German Patent Application Nos. DE 10201202844.7 (filed Feb. 24, 2012) and DE 102012205352.2 (filed Apr. 2, 2012), the entireties of which are incorporated herein by reference. 
     FIELD 
     The invention relates to an adapter for a sensor for measuring a differential signal. 
     BACKGROUND 
     Measuring a differential signal with the use of an oscilloscope is a familiar task in development laboratories and test stations. In order to register the two partial signals of the differential signal, a sensor with two test-contact probes is used, which each register one partial signal and route it to the oscilloscope for further signal processing and display on a screen. 
     Since the two test-contact points, at which the two partial signals of the differential signal are registered with the sensor, provide a certain spacing distance on the printed circuit board which can differentiate between the individual measurements of different differential signals on a printed circuit board, a sensor is required, with which the spacing distance between the two test-contact probes can be matched to the different spacing distance between two test-contact points. 
     A sensor of this kind, of which the test-contact probes can be adjusted to different spacing distances from one another, is known from U.S. Pat. No. 7,102,370 B1. For this purpose, the sensor in the embodiment illustrated in  FIG. 6  provides two rotary elements capable of being rotated relative to one another, which are each connected to a test-contact probe arranged eccentrically with reference to its axis of rotation. 
     With a technical embodiment of this kind of a sensor, a slip can occur under some circumstances at the contact points between the two rotary elements rotatable relative to one another. When the user of the sensor wishes to adjust the spacing distance between the two test-contact probes, this slip disadvantageously leads to a non-simultaneous rotation of the rotary elements about their own axes of rotation and accordingly determines a non-symmetrical position change of the two test-contact elements. Moreover, as a result of the slip, it cannot be guaranteed with a sensor of this kind, that the two test-contact elements will necessarily remain at the spacing distance set by the user. 
     What is needed, therefore, is a sensor for measuring a differential signal, which, on the one hand, guarantees a simultaneous, symmetrical position adjustment of the two test-contact elements as required by the user and, on the other hand, guarantees that the two test contact elements remain at the spacing distance set by the user. 
     SUMMARY 
     Embodiments of the present invention advantageously address the foregoing requirements and needs, as well as others, by providing for a sensor for measuring a differential signal, which, on the one hand, guarantees a simultaneous, symmetrical position adjustment of the two test-contact elements and, on the other hand, guarantees that the two test contact elements remain at the spacing distance. 
     According to example embodiments of the present invention, an adapter comprises two electrically conductive test-contact elements, which are arranged eccentrically in each case relative to an axis of rotation and which each register a partial signal of the differential signal, and two adjustment components each rotatable about one of the two axes of rotation in order to adjust a variable spacing distance between the two test-contact elements, which are arranged according to the invention in a force-fit connection with one another. 
     As a result of the eccentricity of each test-contact element relative to an axis of rotation and as a result of the rotatability of each adjustment component relative to one of the two axes of rotation, it is possible to adjust any required spacing distance between the two test-contact elements in an infinite manner within a given adjustment range, which is specified by twice the length of the eccentricity. By way of example, the adjustment of the variable spacing distance between the two test-contact elements is implemented by adjustment components, which are electrically insulating and which can therefore be touched during the measurement of the differential signal by the fingers of the person using the sensor and are therefore embodied to be adjustable. 
     According to further example embodiments, two adjustment components are connected to one another according to the invention in a force-fit manner. By way of example, the two adjustment components are simultaneously rotatable, and both test-contact elements are therefore always advantageously changed in their position in a symmetrical manner. By way of further example, the force-fit connection between the two adjustment components allows a self-limiting of the adapter, as a result of which, after adjustment by the user, the two test-contact elements remain at a constant spacing distance relative to one another. 
     In a first embodiment of the invention, the force-fit connection between the two adjustment components is implemented by external teeth provided on a substantially rotationally symmetrical element of the two adjustment components, which are arranged in an interlocking engagement with one another. In a second embodiment of the invention, the force-fit connection is realized by frictional forces, which act between two running surfaces embodied on a substantially rotationally symmetrical element of the two adjustment components, which can be coated or provided with elastic strips, such as rubber bands. 
     According to further example embodiments, an electrically conductive shaft rotatable about the axis of rotation of the adjustment component is connected in a rotatable manner to a connection of a sensor base-element, and a test-contact element and an electrically conductive connecting part for the eccentric connection between a shaft and a test-contact element are integrated in each adjustment component. In this manner, on the one hand, an electrical connection is realized between a test-contact element and a connection of the sensor base-element and, on the other hand, a rotatable adjustment of the test-contact element about an axis of rotation extending through the connection of the sensor base-element is realized. 
     By way of example, realizing the eccentricity via a connecting part allows the use of a standard component which, in combination with a shaft, manufactured respectively as a single component, and a test-contact element, can be manufactured more cost-favorably as a multi-part solution than a shaft realized as a single-part solution with an eccentric test-contact element. 
     By way of further example, the two connecting parts, and therefore the two adjustment components, may be orientated relative to one another in such a manner that the test-contact elements are arranged symmetrically for every adjusted spacing distance relative to a plane, which is disposed in the middle of the two shafts at right angles relative to a connecting straight-line between the two shafts. 
     According to further example embodiments, the two test-contact elements can preferably be embodied either as a test-contact probe or as a test-contact socket. 
     According to further example embodiments, in order to compensate irregularities between the two test-contact points at which the two partial signals of the differential signal are registered, the test-contact elements may be mounted in a spring-loaded manner in the axial direction. 
     According to one embodiment, the rotatable connection respectively between a shaft and an associated connection of the sensor base-element is implemented through a recess, which is provided at the end of the shaft facing towards the sensor base-element and into which an electrically conductive pin integrated in a connection of the sensor base-element is inserted. The end of the shaft facing towards the sensor base-element is embodied in a conical manner and preferably provides at least one slot tapering in the direction towards the end of the shaft. The pin integrated in a connection of the sensor base-element preferably provides a pointed end. In this manner, the sensor with its two shafts can be brought into contact with the two pins integrated in the connections of the sensor base-element and released again comparatively readily. Accordingly, this connection guarantees a comparatively firm seating during the implementation of the individual measurements. 
     According to a further embodiment, the adjustment by the user of the variable spacing distance between the two test-contact elements can be implemented in an ergonomic manner by a knob-like widening on the adjustment component directed radially outwards. 
     According to a further embodiment, the electrically insulating embodiment of the two adjustment components can be realized in a cost-favorable manner by using in each case a synthetic-material part manufactured by injection-molding technology. In order to distinguish between the test-contact elements each measuring one partial signal of the differential signal with regard to a correct connection with a connection of the sensor base-element providing a given polarity, the associated adjustment components may each be a different color. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various example embodiments of the invention, providing an adapter for a sensor measuring a differential signal, are explained in detail below with reference to the drawings, wherein like components are labeled with the same reference numbers, and in which: 
         FIG. 1  illustrates a perspective view of a first embodiment of an adapter with test-contact probes, according to example embodiments of the invention; 
         FIG. 2  illustrates a perspective view of a second embodiment of an adapter with test-contact sockets according to example embodiments of the invention; 
         FIG. 3  illustrates a perspective view of a third embodiment of an adapter with test-contact probes according to example embodiments of the invention; 
         FIG. 4  illustrates a perspective view of test-contact probes of an adapter according to example embodiments of the invention arranged eccentrically relative to a shaft corresponding to the first embodiment of  FIG. 1 ; 
         FIG. 5  illustrates a perspective view of a rotatable connection between a shaft associated with an adapter and a pin associated with a connection of a sensor base-element according to example embodiments of the invention; 
         FIG. 6A  illustrates a perspective overview of an adapter detached from a sensor base-element; 
         FIG. 6B  illustrates a perspective overview of an adapter plugged into a sensor base-element; and 
         FIG. 7  illustrates a plan view of the symmetry between the two test-contact elements of the adapter according to example embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Various approaches for a sensor for measuring a differential signal, which, on the one hand, guarantees a simultaneous, symmetrical position adjustment of the two test-contact elements and, on the other hand, guarantees that the two test contact elements remain at the spacing distance, are described. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It is apparent, however, that embodiments of the invention may be practiced without these specific details or with an equivalent arrangement. In other instances, well known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the invention. 
       FIG. 1  illustrates a perspective view of a first embodiment of an adapter with test-contact probes, according to example embodiments of the invention.  FIG. 2  illustrates a perspective view of a second embodiment of an adapter with test-contact sockets according to example embodiments of the invention.  FIG. 3  illustrates a perspective view of a third embodiment of an adapter with test-contact probes according to example embodiments of the invention. 
     With reference to  FIGS. 1 and 2 , an adapter according to example embodiments of the invention in the first and second embodiments, element  15  as shown respectively in  FIG. 1  and  FIG. 2 , each comprises the two adjustment components  1 , and, in the third embodiment, element  15 ′ as shown in  FIG. 3 , comprises the two adjustment components  1 ′, which are each manufactured from a synthetic material using injection-molding technology. In order to distinguish in which connection  8  of the sensor base-element  9  shown in  FIG. 6A  and with which polarity the respective adjustment component  1  or respectively  1 ′ is plugged with one partial signal of the differential signal registered via its associated test-contact element  5 , the two adjustment components  1  and respectively  1 ′ contained in an adapter  15 ,  15 ′ according example embodiments of the invention may each be a different color. 
     In a first embodiment of the invention according to  FIG. 1 , the two adjustment components  1  are arranged in a force-fit connection with one another, in each case via external teeth  3 , which are provided in a given partial angular segment of the cylindrical surface of the substantially rotationally symmetrical body of the two adjustment components  1  and which engage with one another in a geared manner. The same applies for the second embodiment of  FIG. 2 . While spring-loaded probes are provided as the test-contact elements  5  in  FIG. 1 , these are test sockets in  FIG. 2 . 
     In a third embodiment of the invention according to  FIG. 3 , the two adjustment components  1 ′ are arranged in a force-fit connection with one another via the frictional forces which act, for example, between the two rubber bands  4 , which are stretched respectively over the cylindrical running surface of the substantially rotationally symmetrical body of the two adjustment components  1 ′. Instead of rubber bands, a different coating made from rubber or another high-friction material could also be applied to the running surfaces. 
     A test-contact element  5 , a shaft  6  and a connecting part  7 , which connects the test-contact element  5  eccentrically to the shaft  6  mounted in a rotatable manner, are integrated in each adjustment component  1  or respectively  1 ′, according to  FIG. 4  respectively. While the connecting part  7  is preferably completely concealed within each adjustment component  1  or respectively  1 ′, the test-contact element  5  projects outwards at an end surface of the substantially rotationally symmetrical body of each adjustment component  1  or respectively  1 ′, in order to register a partial signal of the differential signal with the end of the test-contact element  5  projecting significantly from each adjustment component  1  or respectively  1 ′ at a test-contact point, for example, on the printed circuit board. The shaft  6  of each adjustment component  1  or respectively  1 ′ is also guided outwards from each adjustment component  1  or respectively  1 ′ at the respectively other end surface of each adjustment component  1  or respectively  1 ′, in order to establish an electrical and mechanical contact with the connection  8  of the sensor base-element  9 . 
     The two adjustment components  1  or respectively  1 ′ of the adapter according to example embodiments of the invention are orientated with reference to one another, in each case for every adjusted spacing distance between the two test-contact elements  5 , in such a manner that the two test-contact elements  5  are arranged symmetrically to a plane  14 , as shown in  FIG. 7 , which is disposed centrally between the two shafts  8  and at right angles to the connecting straight-line between the two shafts  8 . In order to realize this symmetrical orientation of the two test-contact elements  5 , the connecting parts  7  integrated respectively in the two adjustment components  1  or respectively  1 ′ are also arranged symmetrically relative to this plane. 
     To adjust the orientation of the two adjustment components  1  or respectively  1 ′ relative to one another, and accordingly to adjust the spacing distance between the two test-contact elements  5 , which each project from one of the two adjustment components  1  or respectively  1 ′, each adjustment component  1  or respectively  1 ′ provides respectively on the cylindrical surface a knob-like widening  10  directed radially outwards. However, it is also possible that the widening  10  is present only on one of the two adjustment components  1  or respectively  1 ′. 
     The test-contact elements  5  can be embodied as test-contact probes, as illustrated in  FIGS. 1, 3, 4, 6A , in order to contact test-contact points on the printed circuit board, which are characterized by a very small geometric dimension (for example, very narrow conductor strips) or which are surrounded by components projecting very far above the printed circuit board. However, as an alternative, as illustrated in  FIG. 2 , the test-contact elements  5  can be embodied as test-contact sockets, in order to contact test-contact points on posts, pins or wired components or in order to contact a plug contact with two contact pins which are arranged at a given spacing distance from one another. 
     According to example embodiments, the test-contact elements  5  may be mounted in a spring-loaded manner, as indicated in  FIGS. 1, 3, 4, 6A and 6B  by the stepped and two-part embodiment of the test-contact elements  5 . In this manner, irregularities between the two test-contact points, which can be registered with the two test-contact elements  5  of the sensor  9 , can be bridged. 
     According to  FIG. 5 , the rotatable connection respectively between a shaft  6  of the adapter according to example embodiments of the invention and a pin  11  associated with a connection  8  of the sensor base-element  9  comprises a recess  12 , which is provided at an end of each shaft  6  facing towards the sensor base-element  9 , and the pin  11  of a connection  8  of the sensor base-element  9  inserted into this recess  12  and mounted in a rotatable manner. The shaft  6  provides at least one slot  13 , preferably two slots  13  in the region of the recess  12 . Each of these slots  13  tapers in the direction towards the end of the shaft  6  facing the sensor base-element  13 . 
     If no pin  11  is inserted into the recess  12 , the slot  13  closes at the end of the shaft  6  facing the sensor base-element  13 , while, in the case of a pin  11  inserted into the recess  12 , the slot  13  opens at the end of the shaft  6  facing the sensor base-element  13 . Accordingly, the compressive force, which guarantees a secure seating of the pin  11  in the recess  12  of the shaft  6  is exerted by the side walls of the recess  12  of the shaft  6  on the inserted pin  11 . The pin  11  provides a pointed end, so that combining the two shafts  6  of the adapter according to example embodiments of the invention with the two connections  8  of the sensor base-element  9  is readily possible. The compressive force which is exerted by the side walls of the recess  12  of the shaft  6  onto the pin inserted into the recess  12 , is dimensioned in such a manner that, in addition to a secure seating of the pin  11  in the recess  12 , a release of the pin  11  from the recess  12  of the shaft  6  is also readily possible. 
     The pin  11  associated with a connection  8  is arranged concentrically in the center of a substantially sleeve-like connection  8 , as shown in  FIG. 6A . In order to introduce the pin  11  of a connection  8  of the sensor base-element  9  into the recess  12  of the shaft  6  of the adapter according to example embodiments of the invention integrated in an adjustment component  1  or respectively  2 , in the region of the shaft  6 , a sleeve-like recess corresponding to the sleeve-like connection  8  can be provided in each adjustment component  1  or respectively  1 ′. 
     To minimize wear on the rotatable bearing of the pin  11  associated with the connection  8  of the sensor base-element  9  in the recess  12  of the shaft  6  integrated in an adjustment component  1  or respectively  1 ′ of the adapter  15 ,  15 ′ according to example embodiments of the invention, the hard-gilded pin  11  and the soft-gilded shaft  6  are preferably additionally hardened with copper-beryllium. As a result of the softer gilding, the majority of wear takes place not on the pin  11  but rather on the shaft  6 . 
     According to further embodiments, the adapter may be designed in such a manner that minimizes any influence of the adapter on the two partial signals of the differential signal to be measured. In order to minimize any attenuation of the two partial signals in the adapter, the signal paths of the two partial signals within the adapter  15 ,  15 ′ according to example embodiments of the invention are minimized by minimizing the geometric lengths of the portion of the test-contact element  5  disposed in the respective adjustment component  1  or respectively  1 ′, of the connecting part  7  and of the shaft  6 . In order to minimize any charging up of the adapter by charges of the partial signals to be registered, the input capacitances are kept minimal by minimizing the cross-sections of the test-contact elements  5 , the connecting parts  7  and the shafts  6  of the adapter  15 ,  15 ′ according to example embodiments of the invention. 
     In the illustrated embodiments of the adapter  15 ,  15 ′, a bandwidth preferably larger than 5 GHz is realized. The maximum bandwidth within the transmission behavior of the adapter  15 ,  15 ′ according to example embodiments of the invention may be realized through simplification of the geometric embodiment of the test-contact elements  5  integrated in the two adjustment components  1  or respectively  1 ′, of the connecting parts  7 , of the shafts  6  and of the rotatable mounting of the pins  11  associated with the sensor base-element  9  in the recesses  12  of the shafts  6 . 
     According to further embodiments, an improved common-mode suppression between the two partial signals of the differential signal under test is achieved through a symmetrical adjustment of both of the test-contact elements  5  relative to a plane  14 , which is arranged in the center and at right angles to a spacing straight-line between the two rotatably mounted shafts  8 —and therefore symmetrically relative to the two pins  11  of the two connections  8  of the sensor base-element  9 . 
     The invention is not restricted to the embodiments presented. In particular, all combinations of any of the features claimed in the claims, of the features disclosed in the description and the features illustrated in the drawings are also covered by the invention.