Abstract:
A module for removable insertion into a body of an instrument having longitudinal strings, the body defining a transverse cavity extending from a lateral edge. The module includes a base configured to engage the cavity as the module travels along an axis of movement into the cavity. A first ball plunger contact is configured to conductively engage a corresponding first contact plate affixed to the body when the module reaches at a first point in movement along the axis and to remain engaged as the module moves into cavity along the axis of movement. A second ball plunger is configured to conductively engage a corresponding second contact plate affixed to the body when the module reaches a second point displaced inwardly from the first point in movement along the axis and to remain engaged as the module continues to move into cavity along the axis of movement.

Description:
[0001]    This application is a continuation-in-part of an application Ser. No. 11/612,780 of the same title filed with the United States Patent and Trademark Office on Dec. 19, 2006. The instant application incorporates the content and teaching of that application by this reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to musical instruments and, more specifically, to electric guitars. 
       BACKGROUND OF THE INVENTION 
       [0003]    Adolph Rickenbacker invented the electric guitar. The popularity of the electric guitar began with the big band era as amplified instruments became necessary to compete with the loud volumes of the large brass sections common to jazz orchestras of the thirties and forties. Initially, electric guitars consisted primarily of hollow archtop acoustic guitar bodies to which electromagnetic transducers known as pickups had been attached. p Electric guitars, in contrast to acoustic guitars, rely upon movement of strings in operative proximity to a pickup to convert the oscillations of a string into electrical impulses for subsequent conversion into sound. Some hybrid electric-acoustic guitars are also equipped with additional microphones or piezoelectric pickups (transducers) that sense mechanical vibration from the body. The guitar&#39;s magnetic pickups are embedded or “potted” in epoxy or wax to prevent the pickup from having a microphonic effect. 
         [0004]    In 1950, electronics and instrument amplifier maker Clarence Leonidas Fender, better known as Leo Fender, designed the first commercially successful solid-body electric guitar with a single magnetic pickup, which was initially named the “Esquire™”. A deluxe version of the Esquire™ included two single-coil, 6-pole pickups (bridge and neck positions) with tone and volume controls, a pickup selector switch; an output jack mounted on the side of the body. A black bakelite pickguard concealed a number of body routings for pickups and the connecting wiring. This deluxe version of the Esquire™ was initially called the “Broadcaster™” but because Gretsch™ had a drumset marketed with a similar name (Broadkaster™), Fender™ changed the name to “Telecaster™.” In 1954, Fender™ introduced the Fender™ Stratocaster™, or “Strat” as a further deluxe model having an integrated vibrato mechanism, three single-coil pickups, and body comfort contours. A five-way switch allowed the selective activation of combinations of the three pickups to selectably alter the resulting sound. 
         [0005]    By 1957, Gibson™, a rival manufacturer had made a major change to its deluxe electric guitar, the “Les Paul™.” Gibson™ included a novel pickup known as the “humbucker™.” The humbucker™, invented by Seth Lover, is a dual-coil pickup whose two windings are connected out of phase and reverse-wound. The dual coils tend to cancel a 60-cycle induced signal emanating from appliances using 60-cycle power. A humbucker™ also produces a distinctive, more “mellow” tone which appeals to many guitarists. The same effect can be achieved on guitars, such as the Fender™ Stratocaster™, when two single-coil pickups are selected to be active at the same time to cancel the hum. As is evident in this discussion, progress of the electric guitar has been marked by the progress in selection and configuration of the several pickups used to generate the characteristic signal. 
         [0006]    Pickups exploit induced currents in windings to create the signal. Within a pickup, a magnet is located under each steel string. When a string oscillates at a certain frequency in the presence of the magnet, a magnetic field between the string and magnet oscillates. An electromagnetic coil of wire is wrapped around each magnet such that the oscillating magnetic field induces an alternating current at the same frequency within the coil. Selections of materials, such as numbers of windings in the coil, composition of permanent magnets, and dimensions of the several components, give distinct tonal qualities to various models of pickup. 
         [0007]    More recently, many semi-acoustic and acoustic guitars, and some electric guitars and basses, have been fitted with piezoelectric pickups instead of, or in addition to, magnetic pickups. The piezoelectric pickup gives a very wide frequency range output compared to the magnetic pickups and can give large amplitude signals from the strings. The piezoelectric pickup has a very different sound, which some guitarists prefer, and do not receive the 60-cycle hum that affects magnetic pickups. 
         [0008]    A guitarist will often select from among various pickups, a set of pickups which match the tone the guitarist desires to produce when performing a musical selection. Removal and replacement of pickups is a generally technical process including removing the strings, detaching each pickup from the guitar body, and disconnecting and connecting the pickups from internal electronics within the guitar body. Given the elaborate process necessary for replacement of the pickups, a guitarist&#39;s ability to meaningfully compare the relative tonal qualities of distinct sets of pickups is not possible. 
         [0009]    Several inventors have taught mechanisms configured to allow ready removal and replacement of pickups in dockable modules. U.S. Pat. No. 4,425,831 to Lipman, U.S. Pat. No. 5,029,511 to Rosendahl, U.S. Pat. No. 5,252,777 to Allen, U.S. Pat. No. 4,872,386 to Betticare, U.S. Pat. No. 6,253,654 to Mercurio, U.S. Pat. No. 5,563,823 to Dodge, and U.S. Pat. No. 4,854,210 to Palazzolo each teaches modules that are removed by movement perpendicular to a plane the strings define. For instance, Mercurio teaches a rectangular shaped, through-the-body cutout between the neck and bridge to allow the insertion of a module from behind the instrument, drawing the module toward the plane of the strings. Mercurio teaches removal achieved by withdrawing the module away from the string plane through a through-the-body cutout. 
         [0010]    Where movement perpendicular to the plane the strings define is required, only two routes are available, into or out of the guitar body. Movement out of the guitar body as taught by Betticare, Rosendahl, Allen, Lipman, and Palazzolo requires the removal and replacement of the strings along with the necessary retuning of the strings before the guitar can be played. Movement into and through the guitar body as Dodge and Mercurio teach, require the guitarist to remove the guitar from the playing posture as a prerequisite to changing the pickup. In either regard, the guitarist is hampered in comparison because of the transient nature of human recollection of sound. The longer the interval between use of one set of pickups and use of a second set of pickups, the less complete the guitarist&#39;s recollection, thereby impairing the ability to select the appropriate pickups. 
         [0011]    What is missing in the art is an integral module that is readily removable and replaceable to facilitate the comparison of different pickups. 
       SUMMARY OF THE INVENTION 
       [0012]    A module for removable insertion into a body of an instrument having longitudinal strings defines a transverse cavity extending from a lateral edge. The module includes a base configured to engage the cavity. At least one pickup is secured to the base such that upon insertion into the cavity the pickup is in operative proximity to the strings. The pickup has a first and second electrode. A first electrical contact is in first electrical connection to first electrode. A second electrical contact is in second electrical connection to the second electrode. 
         [0013]    The present invention comprises a system for insertion and removal of a pickup module that includes a base upon which at least one pickup resides. An electric guitar body is configured to receive the pickup module in a cavity by movement of the pickup module relative to the guitar in a plane parallel to and spaced apart from a plane defined by strings mounted on the electric guitar. The movement is generally perpendicular to the strings. Advantageously, movement of the module into and out of the guitar can occur without loosening or removing the strings. The strings retain their tuned frequencies as a second module is substituted for a first module according to the invention. 
         [0014]    In accordance with further aspects of the invention, a seller of pickups can conFIG. a first and a second module with selected pickups to facilitate a guitarist&#39;s selection from among a number of pickups at a time of purchase. In an environment where cavities are standardized as among various guitar manufacturers, a guitarist may take his guitar, regardless of manufacturer to the seller&#39;s business to browse among the pickups mounted on the various modules. 
         [0015]    In accordance with yet another aspect of the invention, the supporting electronics such as a modulation group including a tone control, a volume control, and a multi-way switch may be mounted on the module to allow for distinct modulation controls according to the type of pickup used. By way of non-limiting example, where a magnetic pickup is used the modulation controls may include the tone control, the volume control, and the multi-way switch. Where a piezoelectric pickup is mounted on a module, an additional preamplifier may be included to power the pickup. 
         [0016]    As will be readily appreciated from the foregoing summary, the invention provides a system for rapid, ready docking and undocking of a set of pickups. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0017]    Preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings: 
           [0018]      FIG. 1  is a front view of a guitar assembly; 
           [0019]      FIG. 2  is an exploded front view of the guitar assembly showing a pickup module; 
           [0020]      FIG. 3  is an exploded front view of the pickup module showing the base; and 
           [0021]      FIG. 4  is a side view of the pickup module. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]    The principal shortcoming of the current art is that pickups are not readily removed and replaced without requiring a guitarist to remove a guitar from a playing position. The present invention does allow removal and replacement by allowing a pickup module to be removed in a direction generally perpendicular to the primary axis of the guitar as a set of strings define that axis. The module slides in a plane parallel and behind a plane the set of strings define. For purposes of this application the term “lateral movement” shall mean movement that is in a plane parallel to but spaced apart from the plane the strings define and is further along a line generally perpendicular to principal axis of guitar, itself parallel to any one of the strings. 
         [0023]    Referring to  FIG. 1 , a Fender™ Stratocaster™ is set forth as a non-limiting example of the art. A “Les Paul™.” Gibson™ or any of a variety of other electric string instruments including electric basses could be suitably altered to conform to the claimed limitations. Thus, a guitar assembly  10  is familiar to the guitarist and includes a neck  12  drawing a set of strings  18  across a face of a body assembly  15  from a bridge  21  mounted fixedly to a body  16 . On the body  16 , a pickguard  27  extends between the body  16  and the strings  18  and there supports a first pickup  30   a,  a second pickup  30   b,  and a third pickup  30   c  in operative proximity to the strings  18 . Also familiar to the guitarist experienced with the (non-limiting exemplary) Fender™ Stratocaster™ is the placement of a first tone control  33   a  and a second tone control  33   b  along with a volume control  36  and a five-way switch  39 . 
         [0024]    Unlike the standard Fender™ Stratocaster™, however, is the placement of a pickup module  23 , which, rather than the body  16 , supports the pickguard  27  in fixed attachment to a base  24 . The base  24  lends structural support to the pickguard  27  creating the rigid module  23  which, in this non-limiting embodiment, also includes the pickups  30   a,    30   b ,  30   c  and the modulating electronics such as the tone controls  33   a,    33   b,  the volume control  36 , and the five-way switch  39  as well as connecting wiring (not shown). The base  24 , in sliding engagement with the body  16 , facilitates the easy removal of the pickups  30   a,    30   b,    30   c  (and in this non-limiting embodiment the modulating electronics as well). When fully inserted into the body  16 , the module  23  is in electrical contact with an electrical jack  45  that allows connection in electrical continuity with an amplifier (not shown). 
         [0025]    Reference to  FIG. 2 , an exploded view of the exemplary guitar assembly  10  gives greater insight into the workings of the embodiment. The sliding module  23  is shown with its base  24  fixed to the pickguard  27  and together supporting the pickups  30   a,    30   b,    30   c  and the modulating electronics such as the tone controls  33   a,    33   b,  the volume control  36 , and the five-way switch  39  as well as connecting wiring (not shown). Removal of the module  23  from the body assembly  15  reveals both of a shelf  48  and a cavity  51  that the body  16  defines. Configured to suitably envelope reverse ends of the tone controls  33   a,    33   b,  the volume control  36 , and the five-way switch  39  as well as connecting wiring (not shown), the cavity  51  extends laterally to an edge of the body  16  thereby allowing lateral movement of the module  23  without interference. The shelf  48 , on the other hand, is advantageously conformed to the base  24  to suitably support the pickguard  27  and, in turn, the base  24  and pickups  30   a,    30   b,    30   c  in rigid relationship to the strings  18 , thereby preventing variable response based upon a changing distance between the pickups  30   a,    30   b,    30   c  and the strings  18  in use. 
         [0026]    A pair of rail-like tongues  54  extend from the body  16  to slidingly engage grooves  55  ( FIG. 4 ) defined in the base  24  to allow lateral movement of the module  23  relative to the body  16 . In one, non-limiting embodiment, at least one electrical contact plate  63  is provided to allow the pickups  30   a,    30   b,    30   c  to complete a circuit with an amplifier (not shown). Advantageously, the contacts plate  63  is oriented in a plane generally parallel to and spaced apart from the plane the strings  18  define. Being so oriented, the contact plate  63  allows brushing contact with at least one electrical contact (not shown) on the base  24  such that when fully inserted into the body  16 , the module  23  has electrical continuity through the jack  45  ( FIG. 1 ) with the amplifier (not shown). 
         [0027]    The fixed structural relationship between the base  24  and the pickguard  27  that make up the module  23  is observed in an exploded view of the module  23  in  FIG. 3 . The base  24  is configured, not only to conform to the body  16  ( FIGS. 1 ,  2 ) but also a perimeter of the shelf  48  ( FIG. 2 ) against which the base  24  rests when the module  23  is fully inserted into the body  16 . For this reason, the base  24 , when viewed without the pickguard  27  in place is generally elongate and irregular in shape. Shown in phantom relative to the pickguard  27 , the base  24  extends to the pickups  30   a,    30   b,    30   c,  though the pickups  30   a,    30   b,    30   c  are mounted in opposed relationship to the base  24  relative to the pickguard  27 . 
         [0028]    A side view of the module  23 , referring to  FIG. 4 , shows the base  24  attached to the pickguard  27  and fully received into the body assembly  15 . Rail-like tongues  54  inset into the body  16  slidingly engage grooves  55  the base  24  defines. As the module  23  slides on the grooves  55 , pickguard  27 , mounted on the base  24 , supports the pickups  30   a,    30   b,    30   c  holding them at a constant height relative to the strings  18  ( FIGS. 1 ,  2 ), thereby allowing the pickups  30   a,    30   b,    30   c  to pass under the strings  18  ( FIGS. 1 ,  2 ) during insertion or removal of the module  23 . The tongues  54  extending into the groves  55  have been selected as a non-limiting exemplary means of allowing only lateral movement during insertion and removal of the of the module  23  relative to the guitar assembly  15 . Other means are possible to effect lateral movement. For instance, slides (in some embodiments having rollers turning on ball bearings), such as those commonly used on drawers would be equally effective, though the simplicity of the tongue and groove solution is illustrative of a solution that satisfies the issues relating to degrees of movement. 
         [0029]    In this embodiment, the modulating electronics such as the tone controls  33   a,    33   b,  the volume control  36 , and the five-way switch  39  as well as connecting wiring (not shown) are mounted on the module  23 . Where active pickups are used, the power source may be advantageously mounted off of the module and in within the body  16  allowing the module to be changed without changing power supplies. Nothing in the invention requires the mounting on the module, though given the lateral movement of the module and the placement of the modulating electronics relative to the pickups, the non-limiting example is configured to maintain the normal placement of the modulating electronics as in the stock Fender™ Stratocaster™ and therefore the modulating electronics are mounted on the module  23 . 
         [0030]    In an alternate embodiment (not shown), the module extends to the pickups  30   a,    30   b,    30   c,  from the opposite lateral side of the body  24 , drawing the pickups laterally out of the body  24 . The pickups  30   a,    30   b,    30   c  on the module  23  are removed upwardly when the guitar assembly  10  is in the playing position. In this alternate embodiment, the modulating electronics remain mounted on the body and electrical connection is established in a similar manner to the preferred embodiment. In the alternate embodiment, the pickguard  27  is split into two sections  27   a,    27   b  along a line generally parallel to the strings  18 . In other regards, the alternate embodiment shares many of the same limitations as the exemplary embodiment. 
         [0031]    In the exemplary and alternative embodiments, uses of several hardware enhancements insure that when the module  23  is fully inserted into the body  24 , secure, non-rattling engagement occurs. Because unlike the acoustic guitar, an electric guitar produces tones by virtue of the movement of the strings  18  ( FIGS. 1 ,  2 ) relative to the pickups, and not by resonance of the body  16 , complete structural integrity between the module  23  and the body  16  is not necessary. Rather engagement need only be suitably secure to prevent introduction of unwanted vibratory rattles between the module  23  and the body  16 . 
         [0032]    To achieve such non-rattling engagement, the module  23  may be drawn down into contact with the base  24 , by the presence of suitably mated magnets  57  in each of the body  16  and the base  24 . The magnets  57  are suitably oriented to attract one another. Alteratively, a cam lock catch (not shown) may be advantageous in achieving the same non-rattling engagement. In a further alternate embodiment, a turn and lock catch can similarly draw the base  16  into non-rattling engagement with the body  24 . 
         [0033]    In the non-limiting embodiment, ball plungers  60   a,    60   b,  and  60   c  serve two purposes. First, the ball plungers  60   a,    60   b,  and  60   c  serve as a detente, limiting lateral movement of the module  23  relative to the body assembly  15  upon insertion, thereby assuring the guitarist that the module  23  is fully inserted into the body  16  giving tactile feedback to the guitarist with positive engagement. Thus, while performing, the guitarist is assured that the module  23  will not move out of engagement with the body  16 . 
         [0034]    Second, the at least the ball plungers  60   a,    60   b,  and  60   c  connect in electrical continuity to the at least one contact plate  63 ,  78   a,  or  78   b  respectively. In this manner, the pickups  30   a,    30   b,    30   c  are selectively connected to the jack  45  ( FIG. 1 ) allowing continuity with the amplifier (not shown). While the ball plunger  60  is employed in a preferred embodiment, other electrical connections may be advantageously used to allow continuity with the jack  45  ( FIG. 1 ) such as electrical brushes similar in nature to those used in D.C. motors, or pin-type contacts aligned so that their principal axis is parallel to the lateral movement of the module upon insertion and removal of the module  23  relative to the body  24 . 
         [0035]    An alternate embodiment is shown in  FIG. 5 , an exploded front view of the guitar assembly including an alternate fixation device and  FIG. 6  a side view of the pickup module nested in the body. Hardware aspects of the embodiment have been disclosed in U.S. Pat. No. 7,538,269 to van Ekstrom dated May 29, 2009 which is entirely incorporated by this reference. Because this embodiment of the invention shares the general geometry of sliding the sliding module  23  ( FIG. 2 ) is shown with reference to its base  24  (the pick guard  27  together with the pickups  30   a,    30   b,    30   c  and the modulating electronics such as the tone controls and the volume control  33   a,    33   b,    36 , and the five-way switch  39  as well as connecting wiring are not shown for purposes of clarity; they being well illustrated in  FIG. 2 .). In both embodiments, removal of the module  23  from the body assembly  15  reveals both of a shelf  48  and a cavity  51  that the body  16  defines. Visible, affixed to the shelf is a sheath  75  configured to receive the blade  81  which is, in turn, affixed to the module base  24 . The sheath  75  and blade  81  cooperate to form a sliding mount. The blade  81  is configured to nest within the sheath  75  thereby obviating the need for the tongue  54  ( FIG. 4 ) and its corresponding groove  55  ( FIG. 5 ) as set forth in an above described embodiment. 
         [0036]    As is evident in  FIG. 6  the side view of the pickup module showing the alternate fixation device, when in an inserted position, the sheath  75  partially envelops the blade  81  allowing the module  23  ( FIG. 2 ) as shown here by the presence of the base  24  to move in a direction generally perpendicular and offset from the strings (not shown) as in the above described embodiments as the blade  81  moves into and out of nesting engagement with the sheath  75 . The module  23  ( FIG. 2 ) along with its base  24  are in operative engagement when the blade  81  is fully inserted into the sheath  75 . 
         [0037]    For purposes of describing the inventive use at least two ball plungers, and their staggered engagement with at least two contact plates  63 ,  78   a,  or  78   b  respectively Similarly to the above described embodiment, a first ball plunger  60   a  serves as a detente, limiting lateral movement of the module  23  relative to the body assembly  15  upon insertion, thereby assuring the guitarist that the module  23  is fully inserted into the body  16  giving tactile feedback to the guitarist with positive engagement. Thus, while performing, the guitarist is assured that the module  23  will not move out of engagement with the body  16 . 
         [0038]    Second, the at least two ball plungers, and their staggered initiation continuity with at least two contact plates  63 ,  78   a,  or  78   b  respectively assures that amplifiers outside of the body and preamplifiers for the pickups will not experience a power surge. Surges, also known as spikes, are fast, short duration electrical transients in voltage (voltage spikes), current (current spike), or transferred energy (energy spikes) in an electrical circuit. These fast, short duration electrical transients or overvoltages in the electric potential of a circuit are typically caused by closing or opening a switch in a circuit as occurs when the pickups are removed from a circuit including the input of an amplifier. Typically this produces a popping noise from loudspeakers connected to the amplifier. For such sensitive electronics as the high impedance input stage of a quality amplifier, excessive current can flow if this voltage spike exceeds a breakdown voltage at the input, or if it causes avalanche breakdown. In semiconductor junctions, excessive electrical current may destroy or severely weaken that device. 
         [0039]    An electrical circuit functions in a closed loop, giving a return path for the current. To complete the circuit passing through the ball plungers  60   a,    60   b,  and  60   c  and their respective at least two contact plates  63 ,  78   a,  or  78   b  extending between the pickups  30   a,    30   b , and  30   c  ( FIG. 1 ) and the amplifier (not shown), Referring momentarily to  FIGS. 7   a  and  7   b , we see typical circuits that include the inventive configuration of the ball plungers  60   a,    60   b , and  60   c  and their respective at least two contact plates  63 ,  78   a,  or  78   b  in a circuit mounted largely on the pickguard  27  and the shelf  48 . In both of the passive embodiment and the active embodiment, the pickups  30   a,    30   b,  and  30   c  are selectively included in the circuit by operation of the five way switch  30  (or optionally a three-way switch, or no switch at all, the switch not being a necessary part of the inventive configuration). 
         [0040]    A passive pickup consists of a magnet and a coil of wire. When the guitar string vibrates in the magnetic field generated by the pickup, an electrical current is generated. This changing magnetic field is all that is needed to create the current. No outside source of power is required, though the current generated is rather small. 
         [0041]    Active pickups, in contrast, include a small amplifier (or “pre-amp”, since it will be further amplified at a conventional amplifier) that boosts the signal from the pickup. An active pickup generally uses smaller coils of wire making it less susceptible to external noise, yet also offering a “hotter” output due to the pre-amplification stage. Active electronics require power, usually in the form of one or two 9-volt batteries, shown here as DC. The invention is not limited to the shown embodiment but rather is for the explanatory purpose of showing the inclusion of the ball plungers  60   a,    60   b,  and  60   c  and their respective at least two contact plates  63 ,  78   a,  or  78   b,  and their advantageous placement upon the module  23 . In either of the circuits, the placement of the ball plungers  60   a,    60   b,  and  60   c  and their respective at least two contact plates  63 ,  78   a,  or  78   b  is not critical and the spirit of the invention is accomplished by the placement and use of the ball plungers  60   a,    60   b,  and  60   c  and their respective at least two contact plates  63 ,  78   a,  or  78   b  and not in the exact placement in the circuit. 
         [0042]    The placement of the ball plungers  60   a,    60   b,  and  60   c  and their respective at least two contact plates  63 ,  78   a,  or  78   b  enables module to selectively engage each of the ball plungers  60   a,    60   b,  and  60   c  and their respective at least two contact plates  63 ,  78   a,  or  78   b  in a serial order rather than simultaneously. Additionally, only those ball plungers  60   a,    60   b,  and  60   c  and their respective at least two contact plates  63 ,  78   a,  or  78   b  included in the particular circuit, be it active ( FIG. 7   b ) or passive ( FIG. 7   a ), will be engaged in the circuit. Referring to  FIG. 8 , the body is shown and within the body the various contact plates  63 , and within the sheath  75 , contact plates  78   a  and  78   b.  As the module  23  (not shown) slides into and out of the body  15  it is displaced along an axis of movement (here arbitrarily named the x-axis). By selectively displacing the contact places  63 ,  78   a,    78   b  in a direction parallel to the axis of movement, the timing of the conductive engagement of the ball plungers  60   a,    60   b,  and  60   c  and their respective at least two contact plates  63 ,  78   a,  or  78   b  can be staggered to reduce the likelihood of surges selectively connecting first the ground and then the positive contact plate  78   a  for both the passive and the active pickups and then the power positive contact place  78   b  for the active pickups. In this fashion, a module  23  having active pickups can be exchanged for a module  23  having passive pickups, both without danger of surging voltage and the resulting surge in current and allowing the active circuit to only be energized when suitable for energizing pickups. 
         [0043]    By way of demonstration, in  FIG. 9 , an activation waveform is shown for each of the exemplary ball plunger contact plate pair: ballplunger  60   a  and contact plate  63  at waveform  99   a;  ballplunger  60   b  and contact plate  78   a  at waveform  99   b;  and ballplunger  60   c  and contact plate  78   b  at waveform  99   c.  As the module  23  moves along the axis of movement x-axis, the first of the three pairs, ballplunger  60   a  and contact plate  63  makes conductive conduct as shown in waveform&#39;s  99   a  transition from low or off to high or on. As the module&#39;s  23  movement continues along the axis of movement, the second of the three pairs, ballplunger  60   b  and contact plate  78   a  makes conductive conduct as shown in waveform&#39;s  99   b  transition from low or off to high or on. Finally, just as the module  23  slides home, the As the module moves along the axis of movement x-axis, the last of the three pairs, ballplunger  60   c  and contact plate  78   b  makes conductive conduct as shown in waveform&#39;s  99   c  transition from low or off to high or on. The last set also serves as the detente earlier described to retain the module in its proper relation to the body  15 . The exemplary explanation is not the only order in which conductive engagement occurs. All that is important for the invention is that the contacts are displaced from simultaneous conductive engagement in a direction parallel to the axis of movement, and therefore in time as the module  23  moves into or out of the body  16 . 
         [0044]    The scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined by reference to the claims that follow.