Abstract:
Probes and methods for testing electrical circuits are provided. One such probe includes a conductive socket, a conductive spring, and a housing that guides the conductive spring to the conductive socket to form an electrical connection between the spring and the socket. Once such method includes providing a conical and a spring and guiding the spring to the socket via the conical housing. The guiding step ensures that the spring contacts the socket during assembly and, therefore, ensures that a conductive path from the socket to the spring is provided. Methods and other probes are also provided.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to the field of circuit testing, and particularly to probe assemblies used in the testing of circuitry.  
         RELATED ART  
         [0002]    Probe assemblies are used in the design and manufacture of electrical circuits to test the integrity of signals propagating through the connections of the electrical circuits. Typically, probe assemblies include a conductive contact pin, a probe circuit, and a conductive spring mechanism that connects the contact pin to the probe circuit. The contact pin is typically located at an end of the probe assembly and is pressed in contact with a connection of a circuit under test. A signal propagating along the connection of the circuit under test passes through the contact pin and the spring mechanism to the probe circuit, which tests or measures the signal in accordance with techniques known in the art.  
           [0003]    Moreover, as technology has advanced, circuits have decreased in size. To facilitate testing of smaller circuits, the sizes of many probe assemblies have decreased as well. In particular, the contact pin and the spring mechanism for many newer model probe assemblies have significantly decreased in length as compared to older model probe assemblies.  
           [0004]    The decreasing size of probe assemblies has precipitated disadvantages in their manufacturing due, in particular, to the small size of the contact pins and spring mechanisms of the probe assemblies. Indeed, ensuring a reliable connection between a small-scale contact pin and a small-scale spring mechanism during an assembly of a circuit probe can be difficult and problematic. When contact is not made between the contact pin and the spring, signals from the circuit under test are unable to pass to the probe circuit, thereby preventing the circuit probe from operating properly.  
         SUMMARY OF THE INVENTION  
         [0005]    Generally, the present invention provides probes for testing a circuit. A probe in accordance with an exemplary embodiment of the present invention includes a conductive socket adapted to receive a contact pin and a conductive spring. In addition, the probe includes a housing shaped for guiding the spring to the socket to form an electrical connection between the spring and the socket.  
           [0006]    The present invention can also be viewed as providing methods for testing circuitry. One such method can be broadly conceptualized by the following steps: providing a conical housing that includes a conductive socket; providing a spring; and guiding the spring to the socket via the conical housing.  
           [0007]    Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    The invention can be better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other, emphasis instead being placed upon clearly illustrating the principles of the invention. Furthermore, like reference numerals designate corresponding parts throughout the figures.  
         [0009]    [0009]FIG. 1 is an isometric drawing of the probe assembly in accordance with an exemplary embodiment of the present invention.  
         [0010]    [0010]FIG. 2 is an isometric drawing of the probe assembly of FIG. 1 attached to a resistor pin.  
         [0011]    [0011]FIG. 3 is an isometric drawing of the resistor pin depicted in FIG. 2.  
         [0012]    [0012]FIG. 4 is an isometric drawing of the barrel of a probe assembly depicted in FIG.  
         [0013]    [0013]FIG. 5 is an isometric drawing of the conical nose of the probe assembly depicted in FIG. 1.  
         [0014]    [0014]FIG. 6 is an isometric drawing of the conical nose depicted in FIG. 5 illustrating a view of the inner walls of the nose.  
         [0015]    [0015]FIG. 7 is a cross-sectional view of the probe assembly depicted in FIG. 1.  
         [0016]    [0016]FIG. 8 is an isometric drawing of the printed circuit board and spring depicted in FIG. 7.  
         [0017]    FIGS.  9 A- 9 C are consecutive elevation views of insertion of the spring and printed circuit board of FIG. 7 into the conical nose depicted in FIG. 1. FIG. 10 is a flowchart illustrating a circuit testing method as depicted in FIGS.  9 A- 9 C. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]    In general, the present invention involves probe assemblies for testing electrical circuits. FIG. 1 generally depicts a probe assembly  100  in accordance with an embodiment of the present invention.  
         [0019]    The probe assembly  100  includes a conical nose  104  rigidly attached at its base to a cylindrical barrel  102 . At an opposing end, the conical nose  104  includes a socket  106 . The socket  106  shown in FIG. 1 is a cylindrically shaped female that receives a conductive contact pin, which will be described in further detail below. Note that the barrel  102  and the socket  106  are fabricated out of a gold plated conductive metal, although other types of materials may be employed in other embodiments. In addition, the socket  106  includes a slit  103  in the cylindrical wall of the socket  106  that allows for crimping the socket  106  to secure objects placed within the socket  106 .  
         [0020]    [0020]FIG. 2 illustrates the probe assembly  100  when a conductive contact pin assembly  108  is attached to the socket  106  (FIG. 1) of the probe assembly  100 . Note that conductive contact pin  108  includes a resistor pin, although other types of pins can be used. The contact pin assembly  108  attaches to the probe assembly  100  creating a conductive path from the contact point  110  to the socket  106  (FIG. 1).  
         [0021]    A more detailed view of the conductive contact pin assembly  108  is depicted in FIG. 3. In this regard, conductive contact pin assembly  108  includes a hollow conical component  114 . Protruding from within the hollow housing of the conical component  114  is a pin tail  112 . The pin tail  112  is sized and shaped to fit within the socket  106  (FIG. 1) of the probe assembly  100 .  
         [0022]    [0022]FIG. 4 depicts a more detailed view of the barrel  102  of the probe assembly  100  illustrated in FIG. 1. The barrel  102  is a hollow cylinder that receives the base of the conical nose  104  (FIG. 1). As shown by FIG. 4, within the conical nose-receiving end  116  of the barrel  102 , a ledge  118  provides a stop, which allows the barrel  102  to properly retain the base of the conical nose  104  (FIG. 1). The retaining nature of the ledge  118  is discussed in more detail later with reference to FIG. 5 and FIG. 6.  
         [0023]    In this regard, FIG. 5 depicts a more detailed view of the conical nose  104  of the probe assembly  100  that is depicted in FIG. 1. The conical nose  104  includes, at its vertex, a resistor pin tail-receiving cylinder  123 . The nose  104  is sized and shaped to be inserted into a hollow contact pin assembly body  114  of the resistor pin  108  depicted in FIG. 3. When this occurs, the pin tail  112  (FIG. 3) of the resistor pin  108  passes through the socket  106  (FIG. 5). The conductive contact pin assembly  108  and the conical nose  104  are pushed together until the pin tail  112  engages and is stopped by the ledge  120  of the conical housing  104 .  
         [0024]    In addition, the conical nose  104  (FIG. 5) includes an insertion tail  119  that fits within the receiving end  116  (FIG. 4) of the barrel  102 . The ledge  118  within the barrel opening  116  provides a stop preventing the nose  104  from proceeding past the ledge  118  upon insertion of the conical nose  104  into the barrel opening  116 . In addition, the ledge  121  of the conical nose  104  rests upon the lip of the barrel opening  116  further retaining the conical nose  104 .  
         [0025]    [0025]FIG. 6 shows an isometric view from the perspective of the hollow base of the conical nose  104 . As shown by FIG. 6, an inner wall  122  of the conical housing  104  converges to a circular conductive contact, which is the socket  106  (FIG. 5) inserted within the conical housing  104 . Note that convergence of the inner wall  122  terminates at the rear of the socket  106 . As noted herein, the socket  106  is fabricated from a conductive material, for example a gold-plated metal. Therefore, the inner portion at the socket end of the conical housing  104  is conductive. More specifically, the inner portion of the cylinder  123  (FIG. 5) is conductive. Further note that in some embodiments the converging inner wall  122  could be smooth.  
         [0026]    [0026]FIG. 7 illustrates a cross-sectional view of the probe assembly  100  when a conductive contact pin assembly  108  (FIG. 3), the conical nose  104  (FIG. 5), and the barrel  102  (FIG. 4) are interconnected. As shown by FIG. 7, a printed circuit board (PCB)  128  is affixed to the barrel  102 , and a spring  126  is attached at an end of the PCB  128  that is inserted into the conical nose  104 . Therefore, when the conical nose  104  is attached to the barrel  102 , as shown by FIG. 7, the spring  126  abuts the socket  106 . This assembly of the components effectuates a conductive path through which a signal can travel from the tip  110  of the conductive contact pin assembly  108  to the PCB  128  via the socket  106  and the spring  126 .  
         [0027]    In this regard, the pin tail  112  of the pin assembly  108  is conductively coupled to the contact point  110  through a resistor  124 . Furthermore, the pin tail  112  fits within a cavity  113  of the socket  106  and is electrically coupled to the socket  106 . In addition, the socket  106  extends along the length of the cylinder  123  (FIG. 5) of the conical nose  104 , and the spring  126  abuts and is deflected by the socket  106 , thereby forming an electrical connection between the spring  126  and the socket  106 . The spring  126  is attached to a PCB  128  that connects at its opposing end to a coaxial cable (not shown) which in turn is connected to a probe circuit, (not shown).  
         [0028]    With reference to FIG. 7, causing the conductive contact pin  110  to come in contact with an electrical connection of the circuit tests a circuit (not shown). A signal propagating along this connection travels through the conductive pin tail  112  to the conductive socket  106 , and in turn is conducted by the spring  126  to the PCB  128 . The signal is then routed to a probe circuit (not shown) through a coaxial cable (not shown). Note that various tests of the circuit under test can be performed based on the signal. Also note that the signal can be routed from the PCB to a probe circuit for testing by connectors, other than a coaxial cable in other embodiments.  
         [0029]    As shown by FIG. 7, the spring  126  may have a small diameter and may be shaped such that the conductance path through the spring is short in length, which results in an advantageous characteristic of the circuit testing assembly  111 . Such a fabrication and shape of the spring result in a shortened conductive path that inherently exhibits low capacitance and inductance characteristics. Therefore, the speed with which signals can traverse the conductive path increases, and the bandwidth capability of the probe as a whole increases.  
         [0030]    Moreover, in the embodiment depicted, the spring  126  is formed from a small diameter wire and can be rounded on its inserting end to better enable unobstructed insertion into the conical nose  104  (FIG. 1). More specifically, the portion of the spring that comes into contact with the inner wall  122  of the conical nose  104  is rounded or blunt. Making this portion of the spring  126  rounded or blunt helps the spring  126  to travel through the conical housing without engaging the inner wall  122  and becoming snared on the wall thereby preventing contact of the spring  126  with the socket  106 . Note that the spring  126  is made of a metal exhibiting spring qualities, for example berillium copper or music wire. However, the spring  126  shape and material are not limited, and the connection between the socket  106  and the PCB  128  can be effectuated by a spring formed into an alternative shape and/or by a spring having an alternative elemental make-up.  
         [0031]    In addition, the PCB  128  provides a circuit that propagates a signal from the spring  126  to a coaxial cable (not shown) attached at the PCB&#39;s  128  opposing end. A PCB of an embodiment is described in more detail with reference to FIG. 8. However, it should be noted that any circuit that propagates the signal from the spring  126  to a connector that transmits the signal to a probe circuit could be used.  
         [0032]    As shown in an embodiment of FIG. 8, the spring  126  is connected to the PCB  128  at one end. At an opposing end of the PCB  128  is a u-shaped receptacle  136  for receiving a coaxial cable. Note that the ground of the coaxial cable can be soldered to the legs of the u-shaped receptacle, and the center conductor of the coaxial cable can be soldered to the center conductive portion of the PCB  128 . The signal propagates through a capacitor  132  and then a resistor  134 , which is connected to ground. The conductor of the coaxial cable (not shown) then receives the signal.  
         [0033]    An exemplary process for manufacturing the assembly  111  will now be described in more detail. Initially, the barrel  102 , including the spring  126 , is attached to the conical nose  104  such that the spring  126  is positioned abutting the socket  106 . The process of assembling the barrel  102  and the conical nose  104  is now described in more detail with reference to FIG. 9A, FIG. 9B, and FIG. 9C. When viewed consecutively, the figures show the positioning of the spring  126  as the barrel  102  is attached to the conical nose  104 .  
         [0034]    [0034]FIG. 9A shows the spring  126  in an initial position as the barrel is moved toward the base of the conical nose  104 . The spring  126  is within the center of the base of the conical nose  104 . Therefore the spring&#39;s position relative to the conical wall  122  is such that the spring  126  does not contact the conical wall  122 . However, due to misalignments during manufacturing, the spring  126 , in many instances, will actually contact the wall  122  and slide down the surface of the wall  122  toward the socket  106  as the barrel  102  and the nose  104  are pressed together.  
         [0035]    [0035]FIG. 9B shows the spring  126  in an intermediate position as the spring is further pushed within the conical housing  104  toward the socket end of the housing  104  during assembly of the circuit test assembly  111  (FIG. 7). As the spring  126  moves toward the socket  106 , the conical wall  122  of the housing  104  guides the spring  126 , if the spring  126  comes into contact with the wall  122  of the housing  104 . In this regard, the conical wall  122  tapers or converges toward the socket end of the housing, and when the spring  126  encounters the conical wall  122  of the housing  104  as the circuit tester  111  is being assembled, the wall  122  guides the spring in the direction of the socket  106 . FIG. 9C shows the final placement of the spring  126  abutting the socket  106 .  
         [0036]    It should be noted that the configuration of the housing  104  and the spring  126  are such that the likelihood of the spring getting hung on a portion of the housing  104  is reduced. In this regard, the rounded characteristics of the spring  126  help to prevent the spring  126  from catching on the conical surface of the housing  104 . Furthermore, the rounded nature of the spring  126  helps to point the tip of the spring  126  away from the surface of the wall  122  such that the tip does not contact the wall  122 . This helps to ensure that the spring tip does not engage the wall  122  and prevent the spring from reaching the socket  106 . This effect is further enhanced by the uniform or continuous nature of the wall  122 . In this regard, as can be seen by viewing FIGS.  9 A- 9 C, the portion of the wall  122  that guides the spring  126  has no edges or corners that can catch or engage the spring  126  as the spring  126  slides down this continuous portion of the wall surface. Moreover, the converging inner wall  122  and the rounded nature of the spring  126  work in conjunction to ensure that the spring  126  can slide down the surface of the wall  122  and contact the socket  106  creating an electrical path from the socket  106  through the spring  126 .  
         [0037]    Reference will now be made to the flowchart of FIG. 10, which depicts the functionality of an embodiment of a probe assembly  100 . It should be noted that, in some alternative implementations, the functions noted in various blocks of FIG. 10 may occur in an alternative order from which they are depicted in FIG. 10. For example, the respective function of two blocks shown in succession in FIG. 10 may, in fact, be performed substantially concurrently. In other embodiments, the respective functions may be performed in the reverse order.  
         [0038]    As shown in FIG. 10, the circuit testing method  138  can be said to begin at block  142  by inserting a spring  126  into a conical housing. The conical housing has a tapering inner wall that converges to a conductive socket. In this regard, the next block  144  indicates a next step of guiding the conductive spring  126  to the conductive socket  106 . As the spring  126  is guided to the conductive socket  106 , the next block indicates the step of establishing an electrical connection between the spring  126  and the conductive socket. This is accomplished by pressing the spring  126  against the conductive socket  106 . The next step in the circuit testing method includes contacting a circuit under test with a contact point  110 . This contact point  110  is electrically coupled to a contact pin  112  that is, in turn, electrically coupled to the socket  106 . In this regard, a signal present in the circuit under test is conducted to the socket  106 . Thus, block  150  indicates the step of receiving a signal from the circuit under test via the conductive path established between the contact point  110  and the test circuit electrically coupled to the spring  126 .  
         [0039]    It should be emphasized that the above-described embodiments of the present invention are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiment(s) of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.