Abstract:
A terminal connector includes a knob at its outer end. A knob cover snaps into the knob to enable rotation of the knob. The knob cover has resiliently urged lock tabs which snap over lock steps on the knob and into grooves beyond the lock steps. The sides of the lock tabs engage sides of the grooves to transmit torque to the knob. The knob covers are color coded so that a selected color can be installed on a selected knob to indicate its function. An insertion prevention lid is integrally molded over a plug insertion opening of the knob cover to prevent insertion of a connector plug therein. A frangible perimeter of the insertion prevention lid permits its removal to enable insertion of a connector plug.

Description:
This application is a continuation of PCT/JP00/02720 filed Apr. 26, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a terminal connector having a cover for use in electrical connection, specifically in audio and video equipment. 
     2. Description of the Related Art 
     Referring to FIG. 7, a conventional terminal connector, shown generally at  100 ′, includes an electrically conductive terminal plate  14  mounted on an insulative circuit board  10 . A terminal  15  is secured to insulative circuit board  10  by a screw portion  17  threaded through a screw hole  16  in terminal plate  14 . A knob  19 ″, affixed projecting away from terminal  15  enables screwing and unscrewing of screw portion  17  for making electrical connection, as will be explained. Conventional terminal connectors  100 ′, are generally constructed in a four-gang (shown) or eight-gang (not shown) configurations. 
     Circuit board  10  includes four cylindrical portions  11 . Cylindrical portions  11  are integrally formed on a first surface of circuit board  10  and surround part of terminals  15  near the first surface of insulative circuit board  10 . Cylindrical portions  11  help avoid lead wire shorts and reduce the chance of electrical contact with a person or an object. Knob  19 ″ of terminal  15  also protrudes away from the first surface. Cylindrical portions  11  each have at least one lead wire insertion notch  12  in an outer periphery. 
     A through hole  13 , formed in insulative circuit board  10 , accommodates adjustable screw portion  17  of terminal  15 . Screw portion  17  is centered in cylindrical portion  11 . Around through hole  13 , a plurality of insertion holes  20  permit insertion of one or more press-in lock pieces  21  and a terminal portion  22  of terminal plate  14  into selected insertion holes  20  to fix terminal plate  14  firmly to insulative circuit board  10 . 
     A fit hole  25 , shaped to receive plug connection portion  23 , passes through the center of knob  19 ″. A plug insertion opening  26 , having a diameter greater than that of fit hole  25 , is formed at the top of knob  19 ″ for guiding as will be described. 
     A terminal body  59 ′, made from electrically conductive material, includes cylindrical plug connection portion  23 , suitable for accepting insertion of a conventional banana tip, a wire end, or other conductor. Also included in terminal body  59 ′, a collar  18  is pulled down into stabilizing contact with insulative circuit board  10  when screw portion  17  is tightened. Terminal body  59 ′ accepts a press fitted knob  19 ″ to form terminal  15 . 
     Terminal body  59 ′ is conventionally formed by cold forging or a similar process. Through cold forging, conventional cylindrical plug connection portion  23 , collar  18 , and screw portion  17  are simultaneously formed. 
     After integration of terminal plates  14  to insulative circuit board  10 , terminals  15  are threaded into terminal plates  14  through screw holes  16 . When each screw portion  17  is tightened, collar  18  of terminal  15  contacts terminal plate  14  and an end portion of screw portion  17  protrudes below a second surface of insulative circuit board  10 . After tightening, an end portion of screw portion  17  is mechanically flattened to form a preventive bulged portion  31  and disrupt a continuous helical thread formed on screw portion  17 . Preventive bulged portion  31  prevents terminal  15  from disengaging screw hole  16  or from being lost during later adjustment. 
     Once terminal plates  14  and terminals  15  are connected to circuit board  10 , knobs  19 ″ are loosened sufficiently to allow insertion of at least one lead wire (not shown).through insertion notches  12 . When screw portion  17  of terminal  15  is tightened toward screw hole  16  in terminal plate  14 , a bottom surface of collar  18  and a top surface of terminal plate  14  sandwich the lead wire (not shown) for electrical contact. A banana plug (not shown), or other conductor, may be inserted into terminal  15 , through plug insertion opening  26  and into plug connection portion  23 , for electrical connection to the lead wire. More than one lead wire may be captured this way, and connected to a connector inserted into plug connection portion  23  or alternatively to terminal portion  22 . 
     Referring additionally to FIG. 6, conventional terminal connectors  100 ′, positioned now in an eight-gang configuration, illustrate positioning of insertion notches  12  through an outer periphery of terminals  15 . Here, knobs  19 ″ are labeled  19 ″ a  through  19 ″ d,  indicating each individual knobs  19 ″ within the configuration. 
     Referring additionally to FIG. 5, a non-conventional terminal connector  100 , previously developed by the applicant, includes electrically conductive terminal plate  14  mounted to insulative circuit board  10 ′. Terminal  15  is secured to insulative circuit board  10 ′ by screw portion  17  threaded into screw hole  16  in terminal plate  14 . A knob  19 ′, fixed projecting away from terminal  15  enables screwing and unscrewing of screw portion  17  for making electrical connection, as will be explained. 
     Cylindrical portion  11 , surrounding a part of terminal  15  near the first surface of insulative circuit board  10 ′, helps avoid lead wire shorts and reduces the chance of electrical contact with a person or an object. Cylindrical portion  11  is formed cylindrically about a center axis and has at least one wire insertion notch  12  in its outer periphery. Cylindrical portion  11  includes at least one lock portion  38  protruding from an upper edge of cylindrical portion  11  and facing the central axis. Lock portions  38 , combined with retention portions  39  (later described) act to prevent terminal  15  from separating from terminal plate  14 . In this figure, insulative circuit board  10 ′ has four cylindrical portions  11  formed on the first surface. 
     Each terminal  15  comprises knob  19 ′ protruding away from the first surface and generally cylindrical in shape. Fit hole  25  contains plug connection portion  23 , and passes through the center of knob  19 ′. Plug insertion opening  26  is formed at the top of fit hole  25 . A circular recess at the bottom of fit hole  25  engages a collar  18 . Knob  19 ′ is made from an electrically insulating material such as resin. 
     An electrically conductive terminal body  59  is an integrally formed element with plug connection portion  23  at a first end, and a minor diameter portion  42  at a second end. Terminal body  59  is integrally formed from with plug connection portion  23  suitable for accepting the insertion of a conventional banana tip, a wire end, or other conductor. Collar  18  is disposed at a first intermediate location and contacts plug connection portion  23 . A screw portion  17  is disposed at a second intermediate location and contacts a minor diameter portion  42 . 
     Plug connection portion  23 , collar  18 , screw portion  17 , and minor diameter portion  42  all have circular shapes about a common axis. That is, plug connection portion  23  has a cylindrical shape, collar  18  has a disk-like shape, screw portion  17  has a cylindrical-column shape, and minor diameter portion  42  has a cylindrical-column shape. Screw portion  17  contains a continuous helical thread having a minor diameter measured from a central axis of screw portion  17 . Minor diameter portion  42  has a diameter, measured from the same central axis, less than the minor diameter of screw portion  17 . Minor diameter portion  42  serves as a guide as is later described. 
     Knob  19 ′ and terminal body  59  are fixed to each other by both the engagement of collar  18  and the swaging of a top rim of plug connection portion  23  to form a complete terminal  15 . This engagement prevents terminal body  59  and knob  19 ′ from rotating with respect to each other and from losing contact with each other as terminal  15  adjusts. 
     Knob  19 ′, on terminal  15 , has integral circular retention portions  39 , formed around an exterior circumference and projecting away from the central axis. Knob  19 ′ has a diameter, relative to the central axis, smaller than that of lock portions  38  formed on cylindrical portion  11  so as to allow adjustment of terminal  15  within cylindrical portion  11 . 
     The inner diameter of cylindrical portion  11 , relative to the central axis of terminal  15 , is greater than that of retention portions  39  to allow insertion of terminal  15  from the second surface of circuit board  10 ′. However, the inner diameter of lock portions  38  is smaller than the outer diameter of retention portions  39  so as to prevent free passage of terminal  15  away from the first surface of circuit board  10 ′ through cylindrical portion  11 . Together, lock portions  38  and retention portions  39  retain terminal  15 . 
     Formed on the second surface of circuit board  10 ′ are through holes  43 . Through holes  43  have a diameter larger than the inner diameter of cylindrical portion  11 , but smaller than the outer diameter of cylindrical portion  11 . Through holes  43  pierce the first surface of insulative circuit board  10 ′ and accommodate terminal plate  14 . 
     Also formed around through hole  43 , on the second surface of circuit board  10 ′, is a plurality of integral insertion slots  40  with lock steps  41  for guiding and retaining terminal projections  22  of terminal plate  14 . Lock steps  41  are formed about a central axis of through hole  43  perpendicular to terminal portions  22  of terminal plate  14 . 
     Each terminal plate  14 , consisting of an electrically conductive material, is formed as a disk portion having a central axis and contacts collar  18  of terminal  15  around cylindrical threaded screw hole  16 . Screw hole  16  enables threaded electrical contact between terminal  15  with screw portion  17  and terminal plate  14 . 
     In each terminal connector  100 , since minor diameter portion  42  has a diameter smaller than that of screw hole  16 , minor diameter portion  42  functions to align and guide terminal plate  14  during assembly. After assembly of terminal connector  100 , banana clips, wire leads or other contacts may be inserted in plug insertion opening  26  of terminal  15  or through insertion notches  12  of cylindrical portion  11 , to enable electrical contact to terminal projections  22  of terminal plate  14 . 
     Now collectively referring to FIGS. 5 through 7, when such eight or four-gang terminal connectors  100 ,  100 ′ are used, individual knobs  19 ′,  19 ″ may be selectively colored to indicate specific signal use. For example, in FIG. 6 knobs  19 ″ a ,  19 ″ b  may be formed in a red color to indicate a positive signal use, and knobs  19 ″ c ,  19 ″ d  may be colored black to indicate a negative signal use. 
     The multiple terminal connectors  100 ,  100 ′ with pre-labeled knobs  19 ′,  19 ″ present several problems concerning manufacturing, assembly, and later use. 
     First, during assembly, knobs  19 ′,  19 ″ are molded in advance in specific colors according to a predicted use. Once molded, knobs  19 ′,  19 ″ are installed into circuit board  10 ,  10 ′, again according to their predicted use. Thus during assembly, pre-labeled knobs  19 ′,  19 ″ must be pre-positioned thus prohibiting adaptation to real-time customer demand. 
     Second, during assembly, pre-positioning knobs  19 ′,  19 ″ complicates assembly steps and requires additional manufacturing storage. 
     Third, manufacture of pre-colored knobs  19 ′,  19 ″ requires a raw material batch separate from the patch used to form insulative circuit boards  10 ,  10 ′. This complicates the manufacturing process and increases manufacturing or supplier costs. 
     Fourth, during assembly of terminal connectors  100 ,  100 ′ terminals  15  are not replaceable where assembled incorrectly. In FIGS. 6 and 7, bulged portion  31  prevent non-destructive disassembly of terminal  15  from circuit board  10 . In FIG. 5, retention portion  39  and lock portion  38  combined with snap-in terminal plate  14  prevent non-destructive disassembly of terminal  15  from circuit board  10 ′. Thus, preventing salvage of improperly assembled terminal connector  100 ,  100 ′. As a result, even a single improperly assembled terminal connector  100 ,  100 ′ will render a complete four or eight-gang terminal connector defective thereby increasing manufacturing losses and costs. 
     OBJECTS SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a terminal connector allowing color labeling during final assembly. 
     It is a further object of the present invention to provide a terminal connector whose knob is designed to receive a replaceable snap-on cover. 
     It is a further object of the present invention to provide a terminal connector whose knob is designed to receive a replaceable snap-on cover containing an insertion preventive lid. 
     It is a further object of the present invention to provide a terminal connector allowing easy storage, assembly, adjustment, and readjustment that minimizes manufacturing defect rates. 
     It is a further object of the present invention to provide a terminal connector allowing replaceable non-destructive re-labeling by shape or color. 
     The present invention relates to a terminal connector including a knob at its outer end. A knob cover snaps into the knob to enable rotation of the knob. The knob cover has resiliently urged lock tabs which snap over lock steps on the knob and into grooves beyond the lock steps. The sides of the lock tabs engage sides of the grooves to transmit torque to the knob. The knob covers are color coded so that selected colors can be installed on a selected knob to indicate its function. An insertion prevention lid is integrally molded over a plug insertion opening of the knob cover to prevent insertion of a connector plug therein. A frangible perimeter of the insertion prevention lid permits its removal to enable insertion of a connector plug. 
     According to an embodiment of the present invention there is provided a terminal connector comprising: a terminal including a terminal body, a means on a first end of the terminal body for attachment to an external element, a knob on a second end of the terminal body, at least one lock step on an exterior surface of the knob, at least one groove adjacent the lock step in an exterior surface of the knob, a knob cover, the knob cover fitting onto the second end over a portion of the knob, a lock tab resiliently attached to the knob cover, the lock tab resiliently engaging the lock step when the knob cover is pushed onto the knob, and sides of the lock tab engaging sides of the groove to resist relative rotation. 
     According to another embodiment of the present invention there is provided a terminal according wherein: the lock step on the knob extends radially on the exterior surface of the knob, the groove extends from a bottom edge of the lock step, the groove having a first and a second side perpendicular to the bottom edge of the lock step and generally axial to the knob, and the first and second side transmitting torque from the knob cover to the knob. 
     According to another embodiment of the present invention there is provided a terminal connector wherein: the knob cover has a generally cylindrical shape surrounding an axial cavity formed concentric to the knob, the lock tab formed in an interior surface of axial cavity, the lock tab having a top surface and a third and a fourth side orthogonal to the top surface, the top surface engaging the lock step to retain the knob cover on the knob, and the third and fourth side disposed parallel to and engaging the first and second side of the groove thereby transmitting torque from the knob cover to the knob. 
     According to another embodiment of the present invention there is provided a terminal connector wherein the knob cover further comprises: a top portion formed on a top end of the knob cover, a plug insertion opening centered in the top portion axial to the knob, and the plug insertion opening having an inner diameter and permitting plug access into the knob. 
     According to another embodiment of the present invention there is provided a terminal connector wherein the knob cover further comprising: an insertion prevention lid molded across the plug insertion opening, the insertion prevention lid including a frangible portion connecting the insertion preventive lid to the knob cover, the insertion prevention lid being smaller than an inner dimension of the knob, and the frangible portion permitting easy breakage thereof for removing the insertion prevention lid thereby permitting plug access to the plug insertion opening. 
     According to another embodiment of the present invention there is provided a terminal connector wherein: the insertion preventive lid and the frangible portion have at least one integral cross groove extending from a central axis to the inner diameter portion of the plug insertion opening, and the cross groove concentrates breaking stress for the frangible portion thereby facilitating the plug access to the plug insertion opening. 
     According to another embodiment of the present invention there is provided a knob cover comprising: an axial cavity fittable over a knob, a plug insertion opening at an end of the axial cavity, an insertion prevention lid integrally molded across the plug insertion opening, the insertion prevention lid preventing access of a plug to the plug insertion opening, a frangible portion at a perimeter of the insertion prevention lid, and the frangible portion permitting easy breakage thereof for removing the plug insertion prevention lid thereby permitting plug access to the plug insertion opening. 
     According to another embodiment of the present invention there is provided a terminal connector comprising: an insulative circuit board, a plurality of terminals rotatably fixed to a first surface of the insulative circuit board, the terminals each having a knob fixed into a top portion of the terminal, a knob cover replaceably fixed onto a top portion of at least one knob, the knob cover permitting manual rotation of the knob on the terminals for attachment to the circuit board, and the knob cover including a selectable color for identifying a function of its terminal. 
     According to another embodiment of the present invention there is provided a terminal connector wherein: each of the knobs on the insulative circuit board have an identical color. 
     According to another embodiment of the present invention there is provided a terminal connector further comprising: a plurality of lock steps radially disposed on the knobs, a plurality of lock tabs on an interior diameter of the knob cover, and the knob cover fixed onto the knob by elastically engaging each of the lock tabs to each of the lock steps thereby replaceably retaining the knob cover on the knob. 
     According to another embodiment of the present invention there is provided a terminal connector comprising: an insulative circuit board, a plurality of terminal plates affixed to a second side of the insulative circuit board, each the terminal plate having a screw hole, a plurality of terminals each having threaded portions threadably engaged to each terminal plate, means for preventing the terminals from losing threaded engagement to the terminal plates, a knob covering a first portion of each terminal to enable manual rotation of each terminal, a knob cover fitted and fixed to each knob, and each knob cover including a selectable color for identifying a function of its terminal. 
     According to another embodiment of the present invention there is provided a terminal connector wherein: a top portion of each knob cover has an integrally formed plug insertion opening coaxial to each knob, the plug insertion openings having an inner diameter, and an improper insertion preventive lid detachably attached to an inner diameter thereby covering the plug insertion openings. 
     According to another embodiment of the present invention there is provided a terminal connector wherein: a top portion of each knob cover has an integrally formed plug insertion opening coaxial to each knob, the plug insertion opening having an inner diameter, and improper insertion preventive lid detachably attached to an inner diameter thereby covering the plug insertion opening. 
     The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view taken along line A—A of FIG.  2 (A), showing an embodiment of the terminal according to the present invention. 
     FIG.  2 (A) is a plane view of FIG.  1 . 
     FIG.  2 (B) is a sectional view taken along the line B—B of FIG.  1 . 
     FIG. 3 is a sectional view showing another embodiment of the knob cover. 
     FIG. 4 is a plane view showing another embodiment of the knob cover according to the present invention. 
     FIG. 5 is a partially-broken front view of a non-conventional terminal connector. 
     FIG. 6 is a top view of a conventional multiple terminal connector. 
     FIG. 7 is a partial front view of a conventional terminal connector. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, an electrically conductive terminal body  59  is an integrally formed element with a plug connection portion  23  at a first end, and a minor diameter portion  42  at a second end. A collar  18  is disposed at a first intermediate location along terminal body  59 . A threaded screw portion  17  is formed at a second intermediate location, between minor diameter portion  42  and intermediate collar  18 , and is co-axial to minor diameter portion  42 . Plug connection portion  23 , collar  18 , screw portion  17 , and minor diameter portion  42  all have circular shapes about a common axis. That is, plug connection portion  23  has a cylindrical shape, collar  18  has a disk-like shape, screw portion  17  has a cylindrical-column shape, and minor diameter portion has a cylindrical-column shape. 
     A terminal  15  includes a knob  19 , surrounding the first end of terminal body  59  and covering collar  18  and plug connection portion  23 , and a knob cover  46  surrounding a top portion of knob  19 . A fit hole  25  contains plug connection portion  23  and passes through the center of knob  19 . A circular recess at the bottom of fit hole  25  engages collar  18 . Formed at the top of fit hole  25  is a plug insertion opening  26 . Knob  19  may be made from an electrically insulating material such as resin. 
     The electrically conductive terminal body  59  is an integral element with plug connection portion  23  at a first end, and a minor diameter portion  42  at a second end. Terminal body  59  may be formed by a cold forging process or other process. Plug connection portion  23  and plug insertion opening  26  are suitable for accepting the insertion of a conventional banana tip, a wire end, or other conductor. Collar  18  is disposed at a first intermediate location and contacts plug connection portion  23 . 
     Screw portion  17  contains a continuous helical thread having a minor diameter measured from a central axis of screw portion  17 . Minor diameter portion  42  has a diameter, measured from the same central axis, less than the minor diameter of screw portion  17 . Minor diameter portion  42  serves to guide terminal  15  into threaded engagement with an terminal plate (not shown). 
     Knob  19  and terminal body  59  are fixed to each other to form a complete terminal  15 . This engagement prevents terminal body  59  and knob  19  from rotating with respect to each other and from losing contact with each other as terminal  15  adjusts relative to a terminal plate (not shown). 
     Knob  19 , on terminal  15 , has integral retention portions  39 , formed around a bottom exterior circumference and projecting away from a central axis. Circular retention portions  39 , used in conjunction with lock portions (not shown) prevent terminal  15  from releasing threaded engagement with the above described terminal plate. 
     Knob  19 , on terminal  15 , has at least one integral lock step  50  formed perpendicular to the central axis around the outer periphery of knob  19 . Lock steps  50  are formed at intermediate positions between retention portions  39  and the top portion of knob  19 . Between intermediate lock steps  50  and a bottom portion of knob  19 , are anti-slip grooves  51  extend longitudinally and created as drawing dies in the molding process of knob  19 . Anti-slip grooves  51  serve to prevent slips, as will be explained. 
     A knob cover  46 , engaging knob  19  through integrally formed lock tabs  48 , has an outer periphery formed about a central axis coincident to the central axis of knob  19  and terminal body  59 . Knob cover  46  has an internal surface and a top portion  24  defined around a plug insertion opening  47 . Lock tabs  48  are formed on the internal surface of knob cover  46  intermediate between the top portion  24  and a bottom edge of knob cover  46 . Incident to each lock tab  48  is a corresponding tab molding hole  49  formed during the manufacture of knob cover  46 . 
     Plug insertion opening  47 , formed in knob cover  46 , has an inner diameter coaxial to the inner diameter of plug insertion opening  26  formed in knob  19 . Plug insertion openings  26 ,  47  allow insertion of banana connectors, wire connectors or the like into plug connection portion  23  thereby enabling electrical connection to collar  18  and threaded portion  17 . 
     During assembly, knob cover  46  is press-fitted over the top of knob  19  and pressed downward toward retention portions  39  formed on knob  19 . During the downward motion of knob cover  46 , lock tabs  48  contact the outside diameter of knob  19  and transmit expansive hoop-stress to knob cover  46  thereby causing it to elastically expand. As lock tabs  48  pass over lock steps  50  and top portion  24  contacts the top of knob  19 , stored expansive hoop-stress causes elastic contraction of knob cover  46  and the engagement of lock tabs  48  into lock steps  50  and grooves  51 . Lock tabs  48  have a sloped bottom edge to enable easy assembly and horizontal surfaces (relative to the page), to enable firm engagement with lock steps  50  after fitting. 
     Grooves  51 , have a first and a second side, and function to align lock tabs  48  to lock steps  50 . Grooves  51  also function to prevent rotation of knob cover  46  with respect to knob  19 . Lock tabs  48  in knob cover  46  are fixed between the first and second sides of groove  51  and thus prevented from slipping as threaded portion  17  is rotated towards the terminal plate(not shown). 
     As additionally shown in FIGS.  2 (A) and  2 (B), the inner diameters of plug insertion openings  47 ,  26  are axially aligned and provide access to plug connection portion  23 . In this embodiment, knob cover  46  has four contacting lock tabs  48  each with tab molding hole  49 . As described above, each groove  51  formed in knob  19 , having the first and the second side, engages a respective first and second side of each corresponding lock tab  48  and fixes lock tab  48  between the first and second side of each groove  51 . This engagement prevents knob cover  46  from slipping with respect to knob  19  when threaded portion  17  is adjusted. Each lock step  50 , having an lower surface, engages each respective lock tab  48 , having an upper surface, to prevent easy disengagement of knob cover  46  from knob  19  during assembly or later adjustment and use. Greater or lesser numbers of lock tabs  48  may be used as long where a similar result is achieved. 
     In FIGS. 1,  2 (A), and  2 (B), knob cover  46  is shown with a smooth exterior diameter relative to the central axis. However, alternative embodiments of knob cover  46  may include an exterior surface shaped as a convex polygon relative to the central axis thus facilitating operator adjustment. The exterior surface may also be shaped as an identification source for operators during assembly and later use. 
     As additionally shown in FIG. 3, an embodiment of knob cover  46  with top portion  24  contains an integral insertion prevention lid  52 . Insertion prevention lid  52  is formed in a generally disk-like shape and extends radially from the central axis of knob cover  46  to contact top portion  24 . Insertion prevention lid  52  has a diameter d 2  smaller than the inner diameter d 1  of plug connection portion  23  to limit access by certain types of plugs. 
     Knob covers  46 , containing insertion prevention lids  52 , are used to block plug insertion openings  47  when banana plugs should be inserted and not power supply plugs. Conventional power supply plugs (not shown) generally have an outer diameter of at least d 1  and conventional banana plugs (not shown) have a flexible outer diameter able to compress to the diameter of diameter d 1 . Thus insertion prevention lid  52  serves as both a safety device preventing mis-assembly, and as a visual cue to assembly operators. 
     Radially surrounding insertion prevention lid  52  is a frangible thin portion  53  enabling insertion prevention lid  52  to be easily broken by an operator wishing to insert a banana plug into terminal  15 . This facilitates proper and speedy assembly of terminal connectors  100 ,  100 ′, including knob covers  46 , and to limit defects created by operator mistake. 
     As additionally shown in FIG. 4, another embodiment of knob cover  46  contains cross grooves  54  spanning thin portion  53  and insertion prevention lid  52 . Cross grooves  54  span insertion prevention lid  52  and further weaken the connection between thin portion  53 , surrounding insertion prevention lid  52 , and top portion  24  thereby preventing unintended damage to insertion prevention lid  52  and terminal  15 . Knob covers  46 , containing cross grooves  54 , may be used during assembly of terminal connectors  100 ,  100 ′ in electrical distribution devices, thus preventing mistaken insertion of power supply plugs. 
     There are multiple benefits to the improved design of knob  19  and knob cover  46 . 
     First, insertion prevention lid  52 , on knob cover  46 , provides beneficial design over conventionally-known detachable improper insertion preventive O-rings, because no separate part supply need to be maintained. Additionally, the combination of insertion prevention lid into knob cover  46  minimizes operator confusion and eliminates the need to incorporate such a function into the pre-assembled terminal  15 . 
     Second, insertion prevention lid  52 , once broken during the insertion of a banana plug provides a visual aid to later repair operators as to the proper terminal connector  100 ,  100 ′ to use. 
     Third, knob cover  46  covering knob  19  provides a larger outer diameter for gripping by an operator than does the narrower exterior diameter of knob  19 . This minimizes operator strain and enables more rapid adjustment. 
     Fourth, knob cover  46  provides a larger outer diameter for the completed terminal  15  and gives a more pleasing visual appearance to the assembled terminal connectors  100 ,  100 ′ thus influencing customer demand. 
     Fifth, each groove  51 , formed in the outer diameter of knob  19  functions to prevent unwanted rotation of knob cover  46  with respect to terminal  19 . This containment allows secure actuation of terminal  15  relative to a terminal plate and enables rapid operator adjustment during assembly. Under extreme tightening requirements, where the engagement of lock tabs  48  in grooves  51  is found insufficient, both the interior diameter of knob cover  46  and the corresponding exterior diameter of knob  19  may be formed into closely nesting polygons thus providing additional engagement. 
     Sixth, the outer diameter of knob cover  46  is easily adapted for special identification purposes without causing a negative impact on the engagement function of inner diameter lock tabs  48  to lock steps  50 . As a result, the embodiment described for knob cover  46  may easily serve as a general-purpose configuration for general-purpose customers while providing an easily recast special purpose, special design, or special color for larger customers requiring an individualized look. 
     Seventh, knob covers  46  covering knobs  19  serve as a safeguard for an outside cylindrical portion (not shown) positioned between retention portions  39  and a bottom edge of knob cover  46  opposite top portion  24 . This protective function prevents unintended capture of connective wire or other detritus between the knob cover  46  and the cylindrical portion thus minimizing assembly error. 
     Eighth, since knob covers  46  are installed onto knobs  19  of terminals  15  after main assembly of terminal connectors  100 ,  100 ′ it is easy to offer rapid custom final assembly in response to last-minute customer requests. 
     Ninth, since knob covers  46  are installed onto knobs  19  of terminals  15  after main assembly of terminal connectors  100 ,  100 ′, it is easy to stockpile generic unlabeled terminal connectors  100 ,  100 ′ without final assembly during times of low customer demand. During times of sudden customer demand a manufacturer may draw against the stockpile to fill rapid customer demand. Thus providing a business advantage to manufacturers using knob covers  46  with knobs  19  since automated assembly lines are difficult and time consuming to change. As a result, quick response to customer orders are enabled, customer satisfaction is correspondingly increased, and steady labor pool may be maintained. 
     Tenth, re-labeling of terminals  15  on terminal connectors  100 ,  100 ′ is simplified by requiring only the removal of knob cover  46  and replacement with another knob cover  46  rather than a complete replacement of terminal  15 . Additionally, re-labeling knob  19  is less expensive and faster than the disassembly of terminal connector  100 ,  100 ′. Thus, re-labeling prevents a single assembly defect from making the entire four- or eight-gang terminal connector  100 ,  100 ′ defective. 
     Eleventh, since knob covers  46  and knobs  19  are adaptable to both kinds of terminal connectors  100 ,  100 ′, knob covers  46  and knobs  19  offer easy adaptation by a variety of manufacturing services. 
     Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.